CVE-2025-21976

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-21976", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.798Z", "datePublished": "2025-04-01T15:47:07.120Z", "dateUpdated": "2026-10-21T12:36:12.299Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:36:12.299Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: hyperv_fb: Allow graceful removal of framebuffer\n\nWhen a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to\nrelease the framebuffer forcefully. If this framebuffer is in use it\nproduce the following WARN and hence this framebuffer is never released.\n\n[ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40\n< snip >\n[ 44.111289] Call Trace:\n[ 44.111290] <TASK>\n[ 44.111291] ? show_regs+0x6c/0x80\n[ 44.111295] ? __warn+0x8d/0x150\n[ 44.111298] ? framebuffer_release+0x2c/0x40\n[ 44.111300] ? report_bug+0x182/0x1b0\n[ 44.111303] ? handle_bug+0x6e/0xb0\n[ 44.111306] ? exc_invalid_op+0x18/0x80\n[ 44.111308] ? asm_exc_invalid_op+0x1b/0x20\n[ 44.111311] ? framebuffer_release+0x2c/0x40\n[ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb]\n[ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus]\n[ 44.111323] device_remove+0x40/0x80\n[ 44.111325] device_release_driver_internal+0x20b/0x270\n[ 44.111327] ? bus_find_device+0xb3/0xf0\n\nFix this by moving the release of framebuffer and assosiated memory\nto fb_ops.fb_destroy function, so that framebuffer framework handles\nit gracefully.\n\nWhile we fix this, also replace manual registrations/unregistration of\nframebuffer with devm_register_framebuffer."}], "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 local interfaces only \u2014 opening and mmap'ing the `/dev/fbN` character device and the local/administrative device-removal path (sysfs unbind, module unload, or VMBus rescind of the guest's synthetic video device). No network or adjacent-network vector exists for hyperv_fb.\nAC:L - There is no race to win: a process simply holds an mmap of `/dev/fb0`, and the premature `vfree()`/`kvfree()` in `hvfb_remove()` deterministically leaves that mapping and the `info->pagerefs` array pointing at freed memory. Grooming the recycled pages afterwards is under the attacker's control via ordinary allocation pressure.\nPR:L - The party that gains the freed-memory read/write primitive only needs to open and mmap the framebuffer device, which unprivileged seat/console users (logind ACLs), `video`-group members, and graphics-domain processes on embedded/Android-style systems routinely can do. No CAP_SYS_ADMIN is needed to hold the mapping that survives the teardown.\nUI:N - The removal that triggers the free is a device/administrative event \u2014 Hyper-V host-side rescind of the video VMBus device, driver reload during a package update, or automated unbind \u2014 not an action by a victim user, and the attacking process merely has to be mapped when it occurs. This matches the treatment of the identical fbdev hot-unplug-while-mapped class.\nS:U - The corrupted resources (vmalloc pages, the deferred-I/O pageref array, the leaked `fb_info`) are all kernel memory managed by the same security authority as the vulnerable driver. No hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - After `vfree(par->dio_vp)` the surviving userspace mapping still points at pages handed back to the page allocator, so the attacker can read whatever kernel data those pages are subsequently reused for \u2014 slab objects, page tables, credentials \u2014 an effectively arbitrary kernel memory disclosure.\nI:H - The same surviving mapping is writable, giving a page-granularity write primitive into recycled kernel memory, and write faults additionally corrupt the kvfree'd `info->pagerefs` array and lock a destroyed mutex. That combination is a classic path to heap/page-table corruption and control-flow hijack.\nA:H - Unbind with the framebuffer in use produces a `WARN_ON` in `framebuffer_release()` (fatal under panic_on_warn) plus an `fb_info` leak, and subsequent access from the still-open fd faults on freed vmalloc memory, walks a freed pageref array, and locks a destroyed mutex \u2014 resulting in oops/panic."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/video/fbdev/hyperv_fb.c"], "versions": [{"version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "b1a86a5ab0d44160534f495a3630646092d98e27", "status": "affected", "versionType": "git"}, {"version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "4545e2aa121aea304d33903099c03e29ed4fe50a", "status": "affected", "versionType": "git"}, {"version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "a7b583dc99c6cf4a96877017be1d08247e1ef2c7", "status": "affected", "versionType": "git"}, {"version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb", "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/hyperv_fb.c"], "versions": [{"version": "3.10", "status": "affected"}, {"version": "0", "lessThan": "3.10", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.20", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.13.8", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.14", "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": "3.10", "versionEndExcluding": "6.6.160"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.12.20"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.13.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.14"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/b1a86a5ab0d44160534f495a3630646092d98e27"}, {"url": "https://git.kernel.org/stable/c/4545e2aa121aea304d33903099c03e29ed4fe50a"}, {"url": "https://git.kernel.org/stable/c/a7b583dc99c6cf4a96877017be1d08247e1ef2c7"}, {"url": "https://git.kernel.org/stable/c/ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb"}], "title": "fbdev: hyperv_fb: Allow graceful removal of framebuffer", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-21976", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-15T21:43:57.399849Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T21:51:56.270Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-21976", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-15T21:43:57.399849Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T21:43:57.874Z"}}], "cna": {"title": "fbdev: hyperv_fb: Allow graceful removal of framebuffer", "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 local interfaces only \u2014 opening and mmap'ing the `/dev/fbN` character device and the local/administrative device-removal path (sysfs unbind, module unload, or VMBus rescind of the guest's synthetic video device). No network or adjacent-network vector exists for hyperv_fb.\nAC:L - There is no race to win: a process simply holds an mmap of `/dev/fb0`, and the premature `vfree()`/`kvfree()` in `hvfb_remove()` deterministically leaves that mapping and the `info->pagerefs` array pointing at freed memory. Grooming the recycled pages afterwards is under the attacker's control via ordinary allocation pressure.\nPR:L - The party that gains the freed-memory read/write primitive only needs to open and mmap the framebuffer device, which unprivileged seat/console users (logind ACLs), `video`-group members, and graphics-domain processes on embedded/Android-style systems routinely can do. No CAP_SYS_ADMIN is needed to hold the mapping that survives the teardown.\nUI:N - The removal that triggers the free is a device/administrative event \u2014 Hyper-V host-side rescind of the video VMBus device, driver reload during a package update, or automated unbind \u2014 not an action by a victim user, and the attacking process merely has to be mapped when it occurs. This matches the treatment of the identical fbdev hot-unplug-while-mapped class.\nS:U - The corrupted resources (vmalloc pages, the deferred-I/O pageref array, the leaked `fb_info`) are all kernel memory managed by the same security authority as the vulnerable driver. No hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - After `vfree(par->dio_vp)` the surviving userspace mapping still points at pages handed back to the page allocator, so the attacker can read whatever kernel data those pages are subsequently reused for \u2014 slab objects, page tables, credentials \u2014 an effectively arbitrary kernel memory disclosure.\nI:H - The same surviving mapping is writable, giving a page-granularity write primitive into recycled kernel memory, and write faults additionally corrupt the kvfree'd `info->pagerefs` array and lock a destroyed mutex. That combination is a classic path to heap/page-table corruption and control-flow hijack.\nA:H - Unbind with the framebuffer in use produces a `WARN_ON` in `framebuffer_release()` (fatal under panic_on_warn) plus an `fb_info` leak, and subsequent access from the still-open fd faults on freed vmalloc memory, walks a freed pageref array, and locks a destroyed mutex \u2014 resulting in oops/panic."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "b1a86a5ab0d44160534f495a3630646092d98e27", "versionType": "git"}, {"status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "4545e2aa121aea304d33903099c03e29ed4fe50a", "versionType": "git"}, {"status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "a7b583dc99c6cf4a96877017be1d08247e1ef2c7", "versionType": "git"}, {"status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "lessThan": "ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb", "versionType": "git"}], "programFiles": ["drivers/video/fbdev/hyperv_fb.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "3.10"}, {"status": "unaffected", "version": "0", "lessThan": "3.10", "versionType": "semver"}, {"status": "unaffected", "version": "6.6.160", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.20", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.13.8", "versionType": "semver", "lessThanOrEqual": "6.13.*"}, {"status": "unaffected", "version": "6.14", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["drivers/video/fbdev/hyperv_fb.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/b1a86a5ab0d44160534f495a3630646092d98e27"}, {"url": "https://git.kernel.org/stable/c/4545e2aa121aea304d33903099c03e29ed4fe50a"}, {"url": "https://git.kernel.org/stable/c/a7b583dc99c6cf4a96877017be1d08247e1ef2c7"}, {"url": "https://git.kernel.org/stable/c/ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: hyperv_fb: Allow graceful removal of framebuffer\n\nWhen a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to\nrelease the framebuffer forcefully. If this framebuffer is in use it\nproduce the following WARN and hence this framebuffer is never released.\n\n[ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40\n< snip >\n[ 44.111289] Call Trace:\n[ 44.111290] <TASK>\n[ 44.111291] ? show_regs+0x6c/0x80\n[ 44.111295] ? __warn+0x8d/0x150\n[ 44.111298] ? framebuffer_release+0x2c/0x40\n[ 44.111300] ? report_bug+0x182/0x1b0\n[ 44.111303] ? handle_bug+0x6e/0xb0\n[ 44.111306] ? exc_invalid_op+0x18/0x80\n[ 44.111308] ? asm_exc_invalid_op+0x1b/0x20\n[ 44.111311] ? framebuffer_release+0x2c/0x40\n[ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb]\n[ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus]\n[ 44.111323] device_remove+0x40/0x80\n[ 44.111325] device_release_driver_internal+0x20b/0x270\n[ 44.111327] ? bus_find_device+0xb3/0xf0\n\nFix this by moving the release of framebuffer and assosiated memory\nto fb_ops.fb_destroy function, so that framebuffer framework handles\nit gracefully.\n\nWhile we fix this, also replace manual registrations/unregistration of\nframebuffer with devm_register_framebuffer."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.160", "versionStartIncluding": "3.10"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.20", "versionStartIncluding": "3.10"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.13.8", "versionStartIncluding": "3.10"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.14", "versionStartIncluding": "3.10"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:36:12.299Z"}}}, "cveMetadata": {"cveId": "CVE-2025-21976", "state": "PUBLISHED", "dateUpdated": "2026-10-21T12:36:12.299Z", "dateReserved": "2024-12-29T08:45:45.798Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2025-04-01T15:47:07.120Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/video/fbdev/hyperv_fb.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "b1a86a5ab0d44160534f495a3630646092d98e27", "status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "versionType": "git"}, {"lessThan": "4545e2aa121aea304d33903099c03e29ed4fe50a", "status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "versionType": "git"}, {"lessThan": "a7b583dc99c6cf4a96877017be1d08247e1ef2c7", "status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "versionType": "git"}, {"lessThan": "ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb", "status": "affected", "version": "68a2d20b79b105f02dcbc52c211d7e62f98996b7", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/video/fbdev/hyperv_fb.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "3.10"}, {"lessThan": "3.10", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.160", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.20", "versionType": "semver"}, {"lessThanOrEqual": "6.13.*", "status": "unaffected", "version": "6.13.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "6.14", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "AE704F9A-FF6F-4BA0-91F8-FD065BD23F1E", "versionEndExcluding": "6.12.20", "versionStartIncluding": "3.10", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "0A20D4D7-B329-4C68-B662-76062EA7DCF0", "versionEndExcluding": "6.13.8", "versionStartIncluding": "6.13", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*", "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*", "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*", "matchCriteriaId": "66619FB8-0AAF-4166-B2CF-67B24143261D", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*", "matchCriteriaId": "D3D6550E-6679-4560-902D-AF52DCFE905B", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:*", "matchCriteriaId": "45B90F6B-BEC7-4D4E-883A-9DBADE021750", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc6:*:*:*:*:*:*", "matchCriteriaId": "1759FFB7-531C-41B1-9AE1-FD3D80E0D920", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: hyperv_fb: Allow graceful removal of framebuffer\n\nWhen a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to\nrelease the framebuffer forcefully. If this framebuffer is in use it\nproduce the following WARN and hence this framebuffer is never released.\n\n[ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40\n< snip >\n[ 44.111289] Call Trace:\n[ 44.111290] <TASK>\n[ 44.111291] ? show_regs+0x6c/0x80\n[ 44.111295] ? __warn+0x8d/0x150\n[ 44.111298] ? framebuffer_release+0x2c/0x40\n[ 44.111300] ? report_bug+0x182/0x1b0\n[ 44.111303] ? handle_bug+0x6e/0xb0\n[ 44.111306] ? exc_invalid_op+0x18/0x80\n[ 44.111308] ? asm_exc_invalid_op+0x1b/0x20\n[ 44.111311] ? framebuffer_release+0x2c/0x40\n[ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb]\n[ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus]\n[ 44.111323] device_remove+0x40/0x80\n[ 44.111325] device_release_driver_internal+0x20b/0x270\n[ 44.111327] ? bus_find_device+0xb3/0xf0\n\nFix this by moving the release of framebuffer and assosiated memory\nto fb_ops.fb_destroy function, so that framebuffer framework handles\nit gracefully.\n\nWhile we fix this, also replace manual registrations/unregistration of\nframebuffer with devm_register_framebuffer."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: fbdev: hyperv_fb: Permite la eliminaci\u00f3n ordenada del framebuffer. Cuando se desvincula un dispositivo framebuffer de Hyper-V, el controlador hyperv_fb intenta liberarlo forzosamente. Si este framebuffer est\u00e1 en uso, genera la siguiente advertencia y, por lo tanto, nunca se libera. [44.111220] ADVERTENCIA: CPU: 35 PID: 1882 en drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40 &lt; snip &gt; [44.111289] Rastreo de llamadas: [ 44.111290] [ 44.111291] ? show_regs+0x6c/0x80 [ 44.111295] ? __warn+0x8d/0x150 [ 44.111298] ? framebuffer_release+0x2c/0x40 [ 44.111300] ? report_bug+0x182/0x1b0 [ 44.111303] ? handle_bug+0x6e/0xb0 [ 44.111306] ? exc_invalid_op+0x18/0x80 [ 44.111308] ? asm_exc_invalid_op+0x1b/0x20 [ 44.111311] ? framebuffer_release+0x2c/0x40 [ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb] [ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus] [ 44.111323] device_remove+0x40/0x80 [ 44.111325] device_release_driver_internal+0x20b/0x270 [ 44.111327] ? bus_find_device+0xb3/0xf0. Solucione esto trasladando la liberaci\u00f3n del framebuffer y la memoria asociada a la funci\u00f3n fb_ops.fb_destroy, para que el framework del framebuffer lo gestione correctamente. Mientras lo solucionamos, tambi\u00e9n reemplace el registro/desregistro manual del framebuffer con devm_register_framebuffer."}], "id": "CVE-2025-21976", "lastModified": "2026-10-21T13:18:03.923", "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"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-21976", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-15T21:43:57.399849Z", "version": "2.0.3"}}]}, "published": "2025-04-01T16:15:28.973", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/4545e2aa121aea304d33903099c03e29ed4fe50a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a7b583dc99c6cf4a96877017be1d08247e1ef2c7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b1a86a5ab0d44160534f495a3630646092d98e27"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: fbdev: hyperv_fb: Allow graceful removal of framebuffer", "id": "2356664", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2356664"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "details": ["In the Linux kernel, the following vulnerability has been resolved:\nfbdev: hyperv_fb: Allow graceful removal of framebuffer\nWhen a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to\nrelease the framebuffer forcefully. If this framebuffer is in use it\nproduce the following WARN and hence this framebuffer is never released.\n[ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40\n< snip >\n[ 44.111289] Call Trace:\n[ 44.111290] <TASK>\n[ 44.111291] ? show_regs+0x6c/0x80\n[ 44.111295] ? __warn+0x8d/0x150\n[ 44.111298] ? framebuffer_release+0x2c/0x40\n[ 44.111300] ? report_bug+0x182/0x1b0\n[ 44.111303] ? handle_bug+0x6e/0xb0\n[ 44.111306] ? exc_invalid_op+0x18/0x80\n[ 44.111308] ? asm_exc_invalid_op+0x1b/0x20\n[ 44.111311] ? framebuffer_release+0x2c/0x40\n[ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb]\n[ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus]\n[ 44.111323] device_remove+0x40/0x80\n[ 44.111325] device_release_driver_internal+0x20b/0x270\n[ 44.111327] ? bus_find_device+0xb3/0xf0\nFix this by moving the release of framebuffer and assosiated memory\nto fb_ops.fb_destroy function, so that framebuffer framework handles\nit gracefully.\nWhile we fix this, also replace manual registrations/unregistration of\nframebuffer with devm_register_framebuffer."], "name": "CVE-2025-21976", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not 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": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-04-01T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-21976\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-21976\nhttps://lore.kernel.org/linux-cve-announce/2025040147-CVE-2025-21976-340d@gregkh/T"], "threat_severity": "Low"}

{}