{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-89762", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-89762", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-11T19:47:03.601Z", "updatedAt": "2026-10-21T12:48:39.169Z", "importedAt": "2026-10-24T01:58:35.090Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "apparmor: fix cred UAF caused by begin_current_label_crit_section()", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix cred UAF caused by begin_current_label_crit_section()\n\nAppArmor's begin_current_label_crit_section() is a scary function called\nfrom lots of LSM hooks (in particular VFS/socket-related ones) that checks\nif the label referenced by the current creds is marked FLAG_STALE, and if\nso, attempts to use aa_replace_current_label() to replace the creds with an\nupdated version that uses a new label.\n\nThe first problem with this is that it would directly lead to UAF of\n`struct cred` if anything in the kernel takes a pointer to the current\ncreds and accesses these past a security hook invocation that replaces\ncreds, like so:\n```\nconst struct cred *cred = current_cred();\nalloc_file_pseudo(...);\nuid_t uid = cred->euid;\n```\nI don't know if anything in the kernel actually does this, but I think it\nis very surprising that this pattern could lead to UAF.\n\nThe second problem is that things go wrong when aa_replace_current_label()\nruns with overridden credentials. aa_replace_current_label() bails out if\n`current_cred() != current_real_cred()` (mirroring the check in\nproc_pid_attr_write()), but this check can't actually reliably detect\noverridden credentials because the overridden creds can be the same as the\nobjective creds.\n\nSo in approximately the following scenario, things go wrong:\n\n1. task begins with (as both objective and subjective creds),\n with refcount=2\n2. task grabs an extra reference on for overriding\n3. task calls override_creds(), which returns a pointer to the old\n subjective creds ()\n4. task enters AppArmor LSM hook\n5. AppArmor checks that objective/subjective creds are equal\n6. AppArmor replaces both cred pointers with and drops 2 refs on\n \n7. task leaves AppArmor LSM hook\n8. task calls revert_creds()\n9. now task->cred is while task->real_cred is , but the\n task_struct logically holds two references to \n10. another task drops the extra reference on that was used for\n overriding, refcount drops to 0\n11. now task->real_cred points to freed creds\n\nAt this point, any access to current_cred() will be UAF.\n\nI have a test case where I run aa-disable on a profile while a process\nusing that profile is blocked on splice() from a FUSE passthrough file into\na full pipe; after the profile update, the pipe becomes empty, splice()\nresumes, the credentials go out of sync, and a subsequent getuid() syscall\nresults in a KASAN UAF splat.\n\nTo fix this, instead of directly replacing creds, do it via task_work that\nwill run at the end of the current syscall. (The point in time at which the\ncred replacement happens should have no correctness impact; it is just a\nperformance optimization to avoid unnecessarily touching the refcount of\nthe new label.)\n\nNote that AppArmor still performs direct cred replacements in the\nsb_pivotroot LSM hook after this change, and that direct cred replacements\ncan still happen in VFS ->write() callbacks via proc_pid_attr_write().\n\nThere are two options for what to do with aa_dup_task_ctx(): Either\nexplicitly reset new->label_replacement_pending after the entire\naa_task_ctx has been copied, or switch to manually copying members over.\nI am switching to manually copying members over because that should make\nbugs more obvious.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "c75afcd153f6147d3b094f45a1d87e5df7f4f053", "status": "affected", "versionType": "git", "lessThan": "089f10b47843a86fa03a8c20799c9353660e5288" }, { "version": "c75afcd153f6147d3b094f45a1d87e5df7f4f053", "status": "affected", "versionType": "git", "lessThan": "361488984d668235438faac28635f3632351407f" }, { "version": "c75afcd153f6147d3b094f45a1d87e5df7f4f053", "status": "affected", "versionType": "git", "lessThan": "587a6a92b93ec314c583bbf747413af170d42540" }, { "version": "c75afcd153f6147d3b094f45a1d87e5df7f4f053", "status": "affected", "versionType": "git", "lessThan": "580f777d6d9fd07fc034bd1aeba5c30fd48871a2" }, { "version": "c75afcd153f6147d3b094f45a1d87e5df7f4f053", "status": "affected", "versionType": "git", "lessThan": "3f4ae5fab613dca01d6a2a8210dd832e009fcf47" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.36", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.36" }, { "version": "6.6.160", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.109", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.50", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.2.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }