{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-43215", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:55.993Z", "datePublished": "2026-05-06T11:28:17.425Z", "dateUpdated": "2026-08-05T12:26:40.744Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:26:40.744Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix locking usage for tcon fields\n\nWe used to use the cifs_tcp_ses_lock to protect a lot of objects\nthat are not just the server, ses or tcon lists. We later introduced\nsrv_lock, ses_lock and tc_lock to protect fields within the\ncorresponding structs. This was done to provide a more granular\nprotection and avoid unnecessary serialization.\n\nThere were still a couple of uses of cifs_tcp_ses_lock to provide\ntcon fields. In this patch, I've replaced them with tc_lock." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable CIFS/SMB client code is exercised through SMB protocol activity with a remote server, including DFS referral handling, reconnects, cancelled closes, and cached directory lease cleanup. A malicious or compromised SMB server can influence these network-driven paths after a client connects.\nAC:L - The issue is a locking/refcount race, but the remote SMB peer can repeatedly trigger reconnects, delayed/cancelled responses, DFS behavior, and lease/cached-directory activity to exercise the affected paths. There is no rare configuration or uncontrollable one-shot condition required beyond a CIFS mount being in use.\nPR:N - The attacker does not need privileges on the vulnerable client system; they can act as the SMB server or network peer providing crafted behavior to the CIFS client. Although mounting CIFS locally is privileged, that is victim-side setup/user interaction rather than attacker privileges on the impacted host.\nUI:R - Exploitation requires the client system to mount or otherwise use an SMB/CIFS share, which is a victim/user or administrator action. Once connected, the malicious server can drive the vulnerable network paths.\nS:U - The impact is within the same Linux kernel security authority running the CIFS client. This is standard kernel memory corruption/panic potential, not a VM escape or cross-authority boundary bypass.\nC:H - The inconsistent locking can corrupt the tcon reference count and allow use-after-free of `struct cifs_tcon`. Kernel UAF conditions are reasonably capable of being shaped into memory disclosure primitives.\nI:H - The same premature free and later dereference/use of the tcon object creates kernel heap use-after-free memory corruption. Under the required higher-severity rule, this is treated as potentially exploitable for arbitrary write or control-flow compromise.\nA:H - At minimum, refcount corruption and use-after-free of a live CIFS tcon can lead to kernel oops, panic, or hangs in reconnect/close/DFS workqueue paths. The condition can be triggered repeatedly by malicious SMB server behavior while the share is mounted." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/cached_dir.c", "fs/smb/client/smb2misc.c", "fs/smb/client/smb2ops.c", "fs/smb/client/smb2pdu.c", "fs/smb/client/trace.h" ], "versions": [ { "version": "d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8", "lessThan": "953953abb66e52c224057ab91e404284fefeab62", "status": "affected", "versionType": "git" }, { "version": "d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8", "lessThan": "601dd3b79769b38d30b693c40afdb2a4b7edf9d0", "status": "affected", "versionType": "git" }, { "version": "d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8", "lessThan": "3969db6b22e3d90d8c5f22ac1a7fe0350a94c136", "status": "affected", "versionType": "git" }, { "version": "d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8", "lessThan": "8c59eeeeffa1524ef57e173a89a1a3ff539888d5", "status": "affected", "versionType": "git" }, { "version": "d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8", "lessThan": "96c4af418586ee9a6aab61738644366426e05316", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/cached_dir.c", "fs/smb/client/smb2misc.c", "fs/smb/client/smb2ops.c", "fs/smb/client/smb2pdu.c", "fs/smb/client/trace.h" ], "versions": [ { "version": "6.0", "status": "affected" }, { "version": "0", "lessThan": "6.0", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.128", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.75", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.16", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.6", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "6.0", "versionEndExcluding": "6.6.128" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.12.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.18.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.19.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/953953abb66e52c224057ab91e404284fefeab62" }, { "url": "https://git.kernel.org/stable/c/601dd3b79769b38d30b693c40afdb2a4b7edf9d0" }, { "url": "https://git.kernel.org/stable/c/3969db6b22e3d90d8c5f22ac1a7fe0350a94c136" }, { "url": "https://git.kernel.org/stable/c/8c59eeeeffa1524ef57e173a89a1a3ff539888d5" }, { "url": "https://git.kernel.org/stable/c/96c4af418586ee9a6aab61738644366426e05316" } ], "title": "cifs: Fix locking usage for tcon fields", "x_generator": { "engine": "bippy-1.2.0" } } } }