CVE-2026-74513

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74513", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.909Z", "datePublished": "2026-08-15T12:27:34.329Z", "dateUpdated": "2026-10-21T12:45:43.905Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:45:43.905Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndibs: fix use-after-free of dmb_node in loopback attach/detach/unregister\n\ndibs_lo_attach_dmb(), dibs_lo_detach_dmb() and dibs_lo_unregister_dmb()\nlook up the dmb_node under dmb_ht_lock, drop the lock and only then\noperate on the node's refcount. Nothing keeps the node alive across\nthat window: __dibs_lo_unregister_dmb() removes the node from the hash\ntable under the write lock and immediately frees it.\n\nA concurrent final put can therefore free the node between the lookup\nand the refcount operation:\n\nCPU0 (attach) CPU1 (owner unregisters)\n\nread_lock_bh(&dmb_ht_lock)\nfind dmb_node (refcnt == 1)\nread_unlock_bh(&dmb_ht_lock)\n refcount_dec_and_test() 1 -> 0\n write_lock_bh(&dmb_ht_lock)\n hash_del(&dmb_node->list)\n write_unlock_bh(&dmb_ht_lock)\n kfree(dmb_node)\nrefcount_inc_not_zero(&dmb_node->refcnt) <-- use-after-free\n\nThe same window exists for the refcount_dec_and_test() calls in the\ndetach and unregister paths.\n\nClose the race structurally by making hash table membership and the\nrefcount transitions atomic with respect to each other:\n\n- Perform the final refcount_dec_and_test() and hash_del() in a single\n dmb_ht_lock write-side critical section, in both the unregister and\n the detach path. Freeing the node still happens after the lock is\n dropped, which is safe because a node whose refcount reached zero has\n left the hash table and can no longer be found.\n\n- This establishes the invariant that any node found in the hash table\n holds at least one reference, and that the final reference can only\n be dropped under the write lock. dibs_lo_attach_dmb() can thus take\n its reference with a plain refcount_inc() while still holding the\n read lock; refcount_inc_not_zero() is no longer needed.\n\n__dibs_lo_unregister_dmb() no longer touches the hash table and is\nrenamed to dibs_lo_free_dmb() accordingly.\n\nNote: commit cc21191b584c (\"dibs: Move data path to dibs layer\") moved\nthe code to its current location; the race was introduced earlier by\ncommit c3a910f2380f (\"net/smc: implement DMB-merged operations of\nloopback-ism\").\n\nTested SMC-D via ISM and dibs loopback."}], "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 bug is only in the DIBS loopback driver used for same-host SMC-D DMB merge; reachable via AF_SMC connect/accept/close syscalls, not from remote packet handling, and loopback-ism cannot be used across machines.\nAC:L - This is a refcount/hash-table race where an attacker can open multiple SMC loopback connections and concurrently trigger attach, detach, and unregister to control both sides of the window without external timing dependencies.\nPR:L - No capability checks gate AF_SMC socket create/connect/close; any unprivileged local user (including in a user/network namespace with SMC/DIBS loopback enabled) can drive the vulnerable dibs_lo_attach/detach/unregister paths.\nUI:N - Exploitation requires only attacker-controlled SMC socket operations; no victim interaction such as opening files, mounting filesystems, or approving prompts is needed beyond normal daemon availability.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same kernel security boundary; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - Use-after-free on dibs_lo_dmb_node allows operating on freed slab memory; attach then returns cpu_addr/len from the freed node, enabling arbitrary kernel memory disclosure via heap reuse.\nI:H - The UAF permits corrupting refcount and adjacent heap metadata and returning a dangling buffer pointer used as a merged SMC send buffer, enabling arbitrary kernel writes and potential code execution.\nA:H - Concurrent refcount operations on a freed dmb_node can cause kernel oops/panic from invalid refcount access or use of freed folio-backed memory during SMC-D buffer attach/detach teardown."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/dibs/dibs_loopback.c"], "versions": [{"version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "lessThan": "90b2166605a7476007f7c013521d30b0be557cac", "status": "affected", "versionType": "git"}, {"version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "lessThan": "c0837aeace96152d14b17fdd19d70102b6631a7d", "status": "affected", "versionType": "git"}, {"version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "lessThan": "48c073f88c93707089a4214f21cb4c3de5aea6e4", "status": "affected", "versionType": "git"}, {"version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "lessThan": "a10ea943356b9d70c5616a0a06f6fa97cfdaccb1", "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/dibs/dibs_loopback.c"], "versions": [{"version": "6.10", "status": "affected"}, {"version": "0", "lessThan": "6.10", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "6.10", "versionEndExcluding": "6.12.114"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.18.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "7.1.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/90b2166605a7476007f7c013521d30b0be557cac"}, {"url": "https://git.kernel.org/stable/c/c0837aeace96152d14b17fdd19d70102b6631a7d"}, {"url": "https://git.kernel.org/stable/c/48c073f88c93707089a4214f21cb4c3de5aea6e4"}, {"url": "https://git.kernel.org/stable/c/a10ea943356b9d70c5616a0a06f6fa97cfdaccb1"}], "title": "dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/dibs/dibs_loopback.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "90b2166605a7476007f7c013521d30b0be557cac", "status": "affected", "version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "versionType": "git"}, {"lessThan": "c0837aeace96152d14b17fdd19d70102b6631a7d", "status": "affected", "version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "versionType": "git"}, {"lessThan": "48c073f88c93707089a4214f21cb4c3de5aea6e4", "status": "affected", "version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "versionType": "git"}, {"lessThan": "a10ea943356b9d70c5616a0a06f6fa97cfdaccb1", "status": "affected", "version": "c3a910f2380fe294d14e42af66af3d3eed8fecbf", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/dibs/dibs_loopback.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.10"}, {"lessThan": "6.10", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.114", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.44", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "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\ndibs: fix use-after-free of dmb_node in loopback attach/detach/unregister\n\ndibs_lo_attach_dmb(), dibs_lo_detach_dmb() and dibs_lo_unregister_dmb()\nlook up the dmb_node under dmb_ht_lock, drop the lock and only then\noperate on the node's refcount. Nothing keeps the node alive across\nthat window: __dibs_lo_unregister_dmb() removes the node from the hash\ntable under the write lock and immediately frees it.\n\nA concurrent final put can therefore free the node between the lookup\nand the refcount operation:\n\nCPU0 (attach) CPU1 (owner unregisters)\n\nread_lock_bh(&dmb_ht_lock)\nfind dmb_node (refcnt == 1)\nread_unlock_bh(&dmb_ht_lock)\n refcount_dec_and_test() 1 -> 0\n write_lock_bh(&dmb_ht_lock)\n hash_del(&dmb_node->list)\n write_unlock_bh(&dmb_ht_lock)\n kfree(dmb_node)\nrefcount_inc_not_zero(&dmb_node->refcnt) <-- use-after-free\n\nThe same window exists for the refcount_dec_and_test() calls in the\ndetach and unregister paths.\n\nClose the race structurally by making hash table membership and the\nrefcount transitions atomic with respect to each other:\n\n- Perform the final refcount_dec_and_test() and hash_del() in a single\n dmb_ht_lock write-side critical section, in both the unregister and\n the detach path. Freeing the node still happens after the lock is\n dropped, which is safe because a node whose refcount reached zero has\n left the hash table and can no longer be found.\n\n- This establishes the invariant that any node found in the hash table\n holds at least one reference, and that the final reference can only\n be dropped under the write lock. dibs_lo_attach_dmb() can thus take\n its reference with a plain refcount_inc() while still holding the\n read lock; refcount_inc_not_zero() is no longer needed.\n\n__dibs_lo_unregister_dmb() no longer touches the hash table and is\nrenamed to dibs_lo_free_dmb() accordingly.\n\nNote: commit cc21191b584c (\"dibs: Move data path to dibs layer\") moved\nthe code to its current location; the race was introduced earlier by\ncommit c3a910f2380f (\"net/smc: implement DMB-merged operations of\nloopback-ism\").\n\nTested SMC-D via ISM and dibs loopback."}], "id": "CVE-2026-74513", "lastModified": "2026-10-21T13:19:45.107", "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"}]}, "published": "2026-08-15T13:17:56.410", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/48c073f88c93707089a4214f21cb4c3de5aea6e4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/90b2166605a7476007f7c013521d30b0be557cac"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a10ea943356b9d70c5616a0a06f6fa97cfdaccb1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c0837aeace96152d14b17fdd19d70102b6631a7d"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister", "id": "2517065", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2517065"}, "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"}, "cwe": "CWE-825", "details": ["In the Linux kernel, the following vulnerability has been resolved:\ndibs: fix use-after-free of dmb_node in loopback attach/detach/unregister\ndibs_lo_attach_dmb(), dibs_lo_detach_dmb() and dibs_lo_unregister_dmb()\nlook up the dmb_node under dmb_ht_lock, drop the lock and only then\noperate on the node's refcount. Nothing keeps the node alive across\nthat window: __dibs_lo_unregister_dmb() removes the node from the hash\ntable under the write lock and immediately frees it.\nA concurrent final put can therefore free the node between the lookup\nand the refcount operation:\nCPU0 (attach) CPU1 (owner unregisters)\nread_lock_bh(&dmb_ht_lock)\nfind dmb_node (refcnt == 1)\nread_unlock_bh(&dmb_ht_lock)\nrefcount_dec_and_test() 1 -> 0\nwrite_lock_bh(&dmb_ht_lock)\nhash_del(&dmb_node->list)\nwrite_unlock_bh(&dmb_ht_lock)\nkfree(dmb_node)\nrefcount_inc_not_zero(&dmb_node->refcnt) <-- use-after-free\nThe same window exists for the refcount_dec_and_test() calls in the\ndetach and unregister paths.\nClose the race structurally by making hash table membership and the\nrefcount transitions atomic with respect to each other:\n- Perform the final refcount_dec_and_test() and hash_del() in a single\ndmb_ht_lock write-side critical section, in both the unregister and\nthe detach path. Freeing the node still happens after the lock is\ndropped, which is safe because a node whose refcount reached zero has\nleft the hash table and can no longer be found.\n- This establishes the invariant that any node found in the hash table\nholds at least one reference, and that the final reference can only\nbe dropped under the write lock. dibs_lo_attach_dmb() can thus take\nits reference with a plain refcount_inc() while still holding the\nread lock; refcount_inc_not_zero() is no longer needed.\n__dibs_lo_unregister_dmb() no longer touches the hash table and is\nrenamed to dibs_lo_free_dmb() accordingly.\nNote: commit cc21191b584c (\"dibs: Move data path to dibs layer\") moved\nthe code to its current location; the race was introduced earlier by\ncommit c3a910f2380f (\"net/smc: implement DMB-merged operations of\nloopback-ism\").\nTested SMC-D via ISM and dibs loopback.", "A flaw was found in the Linux kernel's dibs module. A race condition exists during the attach, detach, and unregister operations of `dmb_node` objects. This allows a concurrent operation to free a `dmb_node` while another operation attempts to access its reference count, leading to a use-after-free vulnerability. This could result in memory corruption and potentially lead to a denial of service or arbitrary code execution."], "name": "CVE-2026-74513", "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": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "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": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74513\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74513\nhttps://lore.kernel.org/linux-cve-announce/2026081543-CVE-2026-74513-c20c@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[c3a910f2380fe294d14e42af66af3d3eed8fecbf,c0837aeace96152d14b17fdd19d70102b6631a7d)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[c3a910f2380fe294d14e42af66af3d3eed8fecbf,48c073f88c93707089a4214f21cb4c3de5aea6e4)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[c3a910f2380fe294d14e42af66af3d3eed8fecbf,a10ea943356b9d70c5616a0a06f6fa97cfdaccb1)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "6.10"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,6.10)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.44,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.8,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "7.2-rc6"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-08-15T15:30:09.536095+00:00", "updated": "2026-08-21T23:00:14.805535+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}