CVE-2025-40323

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-40323", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.186Z", "datePublished": "2025-12-08T00:46:50.833Z", "dateUpdated": "2026-10-15T22:02:45.798Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:09:36.199Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbcon: Set fb_display[i]->mode to NULL when the mode is released\n\nRecently, we discovered the following issue through syzkaller:\n\nBUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0\nRead of size 4 at addr ff11000001b3c69c by task syz.xxx\n...\nCall Trace:\n <TASK>\n dump_stack_lvl+0xab/0xe0\n print_address_description.constprop.0+0x2c/0x390\n print_report+0xb9/0x280\n kasan_report+0xb8/0xf0\n fb_mode_is_equal+0x285/0x2f0\n fbcon_mode_deleted+0x129/0x180\n fb_set_var+0xe7f/0x11d0\n do_fb_ioctl+0x6a0/0x750\n fb_ioctl+0xe0/0x140\n __x64_sys_ioctl+0x193/0x210\n do_syscall_64+0x5f/0x9c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nBased on experimentation and analysis, during framebuffer unregistration,\nonly the memory of fb_info->modelist is freed, without setting the\ncorresponding fb_display[i]->mode to NULL for the freed modes. This leads\nto UAF issues during subsequent accesses. Here's an example of reproduction\nsteps:\n1. With /dev/fb0 already registered in the system, load a kernel module\n to register a new device /dev/fb1;\n2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP);\n3. Switch console from fb to VGA (to allow normal rmmod of the ko);\n4. Unload the kernel module, at this point fb1's modelist is freed, leaving\n a wild pointer in fb_display[];\n5. Trigger the bug via system calls through fb0 attempting to delete a mode\n from fb0.\n\nAdd a check in do_unregister_framebuffer(): if the mode to be freed exists\nin fb_display[], set the corresponding mode pointer to NULL."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The vulnerability is reached through `ioctl()` on the `/dev/fbN` character device (`FBIOPUT_VSCREENINFO` / `FBIOPUT_CON2FBMAP`), which requires local access to the system. There is no remote or network-facing path into fbcon.\nAC:L - Once a framebuffer has been unregistered leaving a stale `fb_display[i].mode`, triggering the use-after-free is a single deterministic ioctl with no race to win and no memory-layout condition outside the attacker's control. The attacker can additionally groom the freed `fb_modelist` slab with controlled allocations before dereferencing it.\nPR:L - No capability check exists anywhere in the fbdev ioctl path \u2014 access is governed solely by DAC on `/dev/fbN`, which logged-in seat users obtain via logind `uaccess` ACLs or `video`/`graphics` group membership on desktops, kiosks, embedded devices and Android. An unprivileged local user with a console/seat can issue every ioctl involved.\nUI:N - The attacker performs all steps himself via ioctls on the framebuffer device; no victim action is needed. The framebuffer unregistration that creates the stale pointer occurs through ordinary system events such as USB display/dock removal or DRM driver unbind.\nS:U - The corruption and its consequences are confined to kernel memory within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The use-after-free reads a freed slab object that the attacker can reallocate with chosen or sensitive kernel data, and `display_to_var()`/`fb_videomode_to_var()` copy ~15 fields out of it into `info->var`, which is then readable from userspace via `FBIOGET_VSCREENINFO` \u2014 a repeatable kernel heap disclosure primitive.\nI:H - A use-after-free on a groomable kmalloc object permits heap spraying and type confusion with the reallocated victim object; the freed contents also propagate into `fb_check_var`/`fb_set_par` and console resize arithmetic, corrupting kernel state and enabling escalation to control-flow hijack.\nA:H - The reported syzkaller report is a KASAN slab-use-after-free that oopses the task in `fb_mode_is_equal()`; dereferencing the dangling pointer after the slab page is returned to the page allocator produces a kernel panic, and the stale pointer can be re-triggered repeatedly."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/video/fbdev/core/fbcon.c", "drivers/video/fbdev/core/fbmem.c", "include/linux/fbcon.h"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "39c2c1a2773aaf73e56906e5ef670114eb2d354f", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "468f78276a37f4c6499385a4ce28f4f57be6655d", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "c079d42f70109512eee49123a843be91d8fa133f", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "de89d19f4f30d9a8de87b9d08c1bd35cb70576d8", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "a1f3058930745d2b938b6b4f5bd9630dc74b26b7", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/video/fbdev/core/fbcon.c", "drivers/video/fbdev/core/fbmem.c", "include/linux/fbcon.h"], "versions": [{"version": "2.6.12", "status": "affected"}, {"version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.159", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.117", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.58", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.17.8", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.203"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.159"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.117"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.58"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.17.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/39c2c1a2773aaf73e56906e5ef670114eb2d354f"}, {"url": "https://git.kernel.org/stable/c/4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb"}, {"url": "https://git.kernel.org/stable/c/468f78276a37f4c6499385a4ce28f4f57be6655d"}, {"url": "https://git.kernel.org/stable/c/c079d42f70109512eee49123a843be91d8fa133f"}, {"url": "https://git.kernel.org/stable/c/de89d19f4f30d9a8de87b9d08c1bd35cb70576d8"}, {"url": "https://git.kernel.org/stable/c/a1f3058930745d2b938b6b4f5bd9630dc74b26b7"}], "title": "fbcon: Set fb_display[i]->mode to NULL when the mode is released", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-40323", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-15T21:59:20.441719Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T22:02:45.798Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-40323", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-15T21:59:20.441719Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T21:59:21.346Z"}}], "cna": {"title": "fbcon: Set fb_display[i]->mode to NULL when the mode is released", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.8, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The vulnerability is reached through `ioctl()` on the `/dev/fbN` character device (`FBIOPUT_VSCREENINFO` / `FBIOPUT_CON2FBMAP`), which requires local access to the system. There is no remote or network-facing path into fbcon.\nAC:L - Once a framebuffer has been unregistered leaving a stale `fb_display[i].mode`, triggering the use-after-free is a single deterministic ioctl with no race to win and no memory-layout condition outside the attacker's control. The attacker can additionally groom the freed `fb_modelist` slab with controlled allocations before dereferencing it.\nPR:L - No capability check exists anywhere in the fbdev ioctl path \u2014 access is governed solely by DAC on `/dev/fbN`, which logged-in seat users obtain via logind `uaccess` ACLs or `video`/`graphics` group membership on desktops, kiosks, embedded devices and Android. An unprivileged local user with a console/seat can issue every ioctl involved.\nUI:N - The attacker performs all steps himself via ioctls on the framebuffer device; no victim action is needed. The framebuffer unregistration that creates the stale pointer occurs through ordinary system events such as USB display/dock removal or DRM driver unbind.\nS:U - The corruption and its consequences are confined to kernel memory within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The use-after-free reads a freed slab object that the attacker can reallocate with chosen or sensitive kernel data, and `display_to_var()`/`fb_videomode_to_var()` copy ~15 fields out of it into `info->var`, which is then readable from userspace via `FBIOGET_VSCREENINFO` \u2014 a repeatable kernel heap disclosure primitive.\nI:H - A use-after-free on a groomable kmalloc object permits heap spraying and type confusion with the reallocated victim object; the freed contents also propagate into `fb_check_var`/`fb_set_par` and console resize arithmetic, corrupting kernel state and enabling escalation to control-flow hijack.\nA:H - The reported syzkaller report is a KASAN slab-use-after-free that oopses the task in `fb_mode_is_equal()`; dereferencing the dangling pointer after the slab page is returned to the page allocator produces a kernel panic, and the stale pointer can be re-triggered repeatedly."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "39c2c1a2773aaf73e56906e5ef670114eb2d354f", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "468f78276a37f4c6499385a4ce28f4f57be6655d", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "c079d42f70109512eee49123a843be91d8fa133f", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "de89d19f4f30d9a8de87b9d08c1bd35cb70576d8", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "a1f3058930745d2b938b6b4f5bd9630dc74b26b7", "versionType": "git"}], "programFiles": ["drivers/video/fbdev/core/fbcon.c", "drivers/video/fbdev/core/fbmem.c", "include/linux/fbcon.h"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "2.6.12"}, {"status": "unaffected", "version": "0", "lessThan": "2.6.12", "versionType": "semver"}, {"status": "unaffected", "version": "5.15.203", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.159", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.117", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.58", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.17.8", "versionType": "semver", "lessThanOrEqual": "6.17.*"}, {"status": "unaffected", "version": "6.18", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["drivers/video/fbdev/core/fbcon.c", "drivers/video/fbdev/core/fbmem.c", "include/linux/fbcon.h"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/39c2c1a2773aaf73e56906e5ef670114eb2d354f"}, {"url": "https://git.kernel.org/stable/c/4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb"}, {"url": "https://git.kernel.org/stable/c/468f78276a37f4c6499385a4ce28f4f57be6655d"}, {"url": "https://git.kernel.org/stable/c/c079d42f70109512eee49123a843be91d8fa133f"}, {"url": "https://git.kernel.org/stable/c/de89d19f4f30d9a8de87b9d08c1bd35cb70576d8"}, {"url": "https://git.kernel.org/stable/c/a1f3058930745d2b938b6b4f5bd9630dc74b26b7"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbcon: Set fb_display[i]->mode to NULL when the mode is released\n\nRecently, we discovered the following issue through syzkaller:\n\nBUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0\nRead of size 4 at addr ff11000001b3c69c by task syz.xxx\n...\nCall Trace:\n <TASK>\n dump_stack_lvl+0xab/0xe0\n print_address_description.constprop.0+0x2c/0x390\n print_report+0xb9/0x280\n kasan_report+0xb8/0xf0\n fb_mode_is_equal+0x285/0x2f0\n fbcon_mode_deleted+0x129/0x180\n fb_set_var+0xe7f/0x11d0\n do_fb_ioctl+0x6a0/0x750\n fb_ioctl+0xe0/0x140\n __x64_sys_ioctl+0x193/0x210\n do_syscall_64+0x5f/0x9c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nBased on experimentation and analysis, during framebuffer unregistration,\nonly the memory of fb_info->modelist is freed, without setting the\ncorresponding fb_display[i]->mode to NULL for the freed modes. This leads\nto UAF issues during subsequent accesses. Here's an example of reproduction\nsteps:\n1. With /dev/fb0 already registered in the system, load a kernel module\n to register a new device /dev/fb1;\n2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP);\n3. Switch console from fb to VGA (to allow normal rmmod of the ko);\n4. Unload the kernel module, at this point fb1's modelist is freed, leaving\n a wild pointer in fb_display[];\n5. Trigger the bug via system calls through fb0 attempting to delete a mode\n from fb0.\n\nAdd a check in do_unregister_framebuffer(): if the mode to be freed exists\nin fb_display[], set the corresponding mode pointer to NULL."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.203", "versionStartIncluding": "2.6.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.159", "versionStartIncluding": "2.6.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.117", "versionStartIncluding": "2.6.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.58", "versionStartIncluding": "2.6.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.17.8", "versionStartIncluding": "2.6.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18", "versionStartIncluding": "2.6.12"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:09:36.199Z"}}}, "cveMetadata": {"cveId": "CVE-2025-40323", "state": "PUBLISHED", "dateUpdated": "2026-10-15T22:02:45.798Z", "dateReserved": "2025-04-16T07:20:57.186Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2025-12-08T00:46:50.833Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/video/fbdev/core/fbcon.c", "drivers/video/fbdev/core/fbmem.c", "include/linux/fbcon.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "39c2c1a2773aaf73e56906e5ef670114eb2d354f", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "468f78276a37f4c6499385a4ce28f4f57be6655d", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "c079d42f70109512eee49123a843be91d8fa133f", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "de89d19f4f30d9a8de87b9d08c1bd35cb70576d8", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "a1f3058930745d2b938b6b4f5bd9630dc74b26b7", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/video/fbdev/core/fbcon.c", "drivers/video/fbdev/core/fbmem.c", "include/linux/fbcon.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "2.6.12"}, {"lessThan": "2.6.12", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.203", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.159", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.117", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.58", "versionType": "semver"}, {"lessThanOrEqual": "6.17.*", "status": "unaffected", "version": "6.17.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "6.18", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbcon: Set fb_display[i]->mode to NULL when the mode is released\n\nRecently, we discovered the following issue through syzkaller:\n\nBUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0\nRead of size 4 at addr ff11000001b3c69c by task syz.xxx\n...\nCall Trace:\n <TASK>\n dump_stack_lvl+0xab/0xe0\n print_address_description.constprop.0+0x2c/0x390\n print_report+0xb9/0x280\n kasan_report+0xb8/0xf0\n fb_mode_is_equal+0x285/0x2f0\n fbcon_mode_deleted+0x129/0x180\n fb_set_var+0xe7f/0x11d0\n do_fb_ioctl+0x6a0/0x750\n fb_ioctl+0xe0/0x140\n __x64_sys_ioctl+0x193/0x210\n do_syscall_64+0x5f/0x9c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nBased on experimentation and analysis, during framebuffer unregistration,\nonly the memory of fb_info->modelist is freed, without setting the\ncorresponding fb_display[i]->mode to NULL for the freed modes. This leads\nto UAF issues during subsequent accesses. Here's an example of reproduction\nsteps:\n1. With /dev/fb0 already registered in the system, load a kernel module\n to register a new device /dev/fb1;\n2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP);\n3. Switch console from fb to VGA (to allow normal rmmod of the ko);\n4. Unload the kernel module, at this point fb1's modelist is freed, leaving\n a wild pointer in fb_display[];\n5. Trigger the bug via system calls through fb0 attempting to delete a mode\n from fb0.\n\nAdd a check in do_unregister_framebuffer(): if the mode to be freed exists\nin fb_display[], set the corresponding mode pointer to NULL."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nfbcon: Establecer fb_display[i] -> mode a NULL cuando el modo es liberado\n\nRecientemente, descubrimos el siguiente problema a trav\u00e9s de syzkaller:\n\nBUG: KASAN: slab-uso despu\u00e9s de liberaci\u00f3n en fb_mode_is_equal+0x285/0x2f0\nLectura de tama\u00f1o 4 en la direcci\u00f3n ff11000001b3c69c por la tarea syz.xxx\n...\nTraza de Llamada:\n <TAREA>\n dump_stack_lvl+0xab/0xe0\n print_address_description.constprop.0+0x2c/0x390\n print_report+0xb9/0x280\n kasan_report+0xb8/0xf0\n fb_mode_is_equal+0x285/0x2f0\n fbcon_mode_deleted+0x129/0x180\n fb_set_var+0xe7f/0x11d0\n do_fb_ioctl+0x6a0/0x750\n fb_ioctl+0xe0/0x140\n __x64_sys_ioctl+0x193/0x210\n do_syscall_64+0x5f/0x9c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nBasado en la experimentaci\u00f3n y el an\u00e1lisis, durante la anulaci\u00f3n del registro del framebuffer, solo se libera la memoria de fb_info -> modelist, sin establecer el fb_display[i] -> mode correspondiente a NULL para los modos liberados. Esto lleva a problemas de UAF durante accesos posteriores. Aqu\u00ed hay un ejemplo de pasos de reproducci\u00f3n:\n1. Con /dev/fb0 ya registrado en el sistema, cargar un m\u00f3dulo del kernel para registrar un nuevo dispositivo /dev/fb1;\n2. Establecer el modo de fb1 al array global fb_display[] (a trav\u00e9s de FBIOPUT_CON2FBMAP);\n3. Cambiar la consola de fb a VGA (para permitir el rmmod normal del ko);\n4. Descargar el m\u00f3dulo del kernel, en este punto la modelist de fb1 es liberada, dejando un puntero 'wild' en fb_display[];\n5. Activar el bug a trav\u00e9s de llamadas al sistema mediante fb0 intentando eliminar un modo de fb0.\n\nA\u00f1adir una verificaci\u00f3n en do_unregister_framebuffer(): si el modo a liberar existe en fb_display[], establecer el puntero de modo correspondiente a NULL."}], "id": "CVE-2025-40323", "lastModified": "2026-10-15T22:19:08.307", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-40323", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-15T21:59:20.441719Z", "version": "2.0.3"}}]}, "published": "2025-12-08T01:16:05.067", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/39c2c1a2773aaf73e56906e5ef670114eb2d354f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/468f78276a37f4c6499385a4ce28f4f57be6655d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a1f3058930745d2b938b6b4f5bd9630dc74b26b7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c079d42f70109512eee49123a843be91d8fa133f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/de89d19f4f30d9a8de87b9d08c1bd35cb70576d8"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Deferred"}

{"bugzilla": {"description": "kernel: fbcon: Set fb_display[i]->mode to NULL when the mode is released", "id": "2419883", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2419883"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "details": ["No description is available for this CVE."], "name": "CVE-2025-40323", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-12-08T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-40323\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-40323\nhttps://lore.kernel.org/linux-cve-announce/2025120824-CVE-2025-40323-047f@gregkh/T"], "threat_severity": "Moderate"}

{"created": "2026-04-20T16:15:11.022051+00:00", "updated": "2026-08-04T09:15:03.482388+00:00", "vendors": [], "weaknesses": ["CWE-416"]}