{"id":"CVE-2026-43499","state":"PUBLISHED","title":"rtmutex: Use waiter::task instead of current in remove_waiter()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nrtmutex: Use waiter::task instead of current in remove_waiter()\n\nremove_waiter() is used by the slowlock paths, but it is also used for\nproxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from\nfutex_requeue().\n\nIn the latter case waiter::task is not current, but remove_waiter()\noperates on current for the dequeue operation. That results in several\nproblems:\n\n  1) the rbtree dequeue happens without waiter::task::pi_lock being held\n\n  2) the waiter task's pi_blocked_on state is not cleared, which leaves a\n     dangling pointer primed for UAF around.\n\n  3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter\n     task\n\nUse waiter::task instead of current in all related operations in\nremove_waiter() to cure those problems.\n\n[ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the\n  \tchangelog ]","publishedAt":"2026-05-21T12:17:49.281Z","updatedAt":"2026-10-15T01:19:29.734Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"f3fa3424bceb128d2be4b3745506b22844b87db7","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"d8cce4773c2b23d819baf5abedc62f7b430e8745","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"8a1fc8d698ac5e5916e3082a0f74450d71f9611f","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"6d52dfcb2a5db86e346cf51f8fcf2071b8085166","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"3fb7394a837740770f0d6b4b30567e60786a63f2","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"88614876370aac8ad1050ad785a4c095ba17ac11","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"3bfdc63936dd4773109b7b8c280c0f3b5ae7d349","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/locking/rtmutex.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.39","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.39","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.140","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.86","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/locking/rtmutex.c"]}],"references":["https://git.kernel.org/stable/c/f3fa3424bceb128d2be4b3745506b22844b87db7","https://git.kernel.org/stable/c/838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd","https://git.kernel.org/stable/c/d8cce4773c2b23d819baf5abedc62f7b430e8745","https://git.kernel.org/stable/c/8a1fc8d698ac5e5916e3082a0f74450d71f9611f","https://git.kernel.org/stable/c/6d52dfcb2a5db86e346cf51f8fcf2071b8085166","https://git.kernel.org/stable/c/3fb7394a837740770f0d6b4b30567e60786a63f2","https://git.kernel.org/stable/c/88614876370aac8ad1050ad785a4c095ba17ac11","https://git.kernel.org/stable/c/3bfdc63936dd4773109b7b8c280c0f3b5ae7d349","http://www.openwall.com/lists/oss-security/2026/07/08/12","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43499.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43499","state":"PUBLISHED","datePublished":"2026-05-21T12:17:49.281Z","dateUpdated":"2026-10-15T01:19:29.734Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:56.014Z"},"containers":{"cna":{"title":"rtmutex: Use waiter::task instead of current in remove_waiter()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nrtmutex: Use waiter::task instead of current in remove_waiter()\n\nremove_waiter() is used by the slowlock paths, but it is also used for\nproxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from\nfutex_requeue().\n\nIn the latter case waiter::task is not current, but remove_waiter()\noperates on current for the dequeue operation. That results in several\nproblems:\n\n  1) the rbtree dequeue happens without waiter::task::pi_lock being held\n\n  2) the waiter task's pi_blocked_on state is not cleared, which leaves a\n     dangling pointer primed for UAF around.\n\n  3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter\n     task\n\nUse waiter::task instead of current in all related operations in\nremove_waiter() to cure those problems.\n\n[ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the\n  \tchangelog ]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"f3fa3424bceb128d2be4b3745506b22844b87db7","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"d8cce4773c2b23d819baf5abedc62f7b430e8745","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"8a1fc8d698ac5e5916e3082a0f74450d71f9611f","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"6d52dfcb2a5db86e346cf51f8fcf2071b8085166","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"3fb7394a837740770f0d6b4b30567e60786a63f2","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"88614876370aac8ad1050ad785a4c095ba17ac11","versionType":"git"},{"version":"8161239a8bcce9ad6b537c04a1fa3b5c68bae693","status":"affected","lessThan":"3bfdc63936dd4773109b7b8c280c0f3b5ae7d349","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/locking/rtmutex.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.39","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.39","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.140","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.86","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/locking/rtmutex.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f3fa3424bceb128d2be4b3745506b22844b87db7"},{"url":"https://git.kernel.org/stable/c/838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd"},{"url":"https://git.kernel.org/stable/c/d8cce4773c2b23d819baf5abedc62f7b430e8745"},{"url":"https://git.kernel.org/stable/c/8a1fc8d698ac5e5916e3082a0f74450d71f9611f"},{"url":"https://git.kernel.org/stable/c/6d52dfcb2a5db86e346cf51f8fcf2071b8085166"},{"url":"https://git.kernel.org/stable/c/3fb7394a837740770f0d6b4b30567e60786a63f2"},{"url":"https://git.kernel.org/stable/c/88614876370aac8ad1050ad785a4c095ba17ac11"},{"url":"https://git.kernel.org/stable/c/3bfdc63936dd4773109b7b8c280c0f3b5ae7d349"}],"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 vulnerable code is reached through the futex(2) syscall (FUTEX_CMP_REQUEUE_PI → futex_requeue → rt_mutex_start_proxy_lock), which requires local access to issue syscalls and is not reachable over any network.\nAC:L - The attacker controls all the threads and PI-futexes involved and can deterministically construct the deadlock-detection error that drives the proxy-lock rollback into remove_waiter(); the resulting UAF/corruption is reliably triggerable without depending on conditions outside the attacker's control.\nPR:L - Any basic unprivileged local user can call futex() with FUTEX_CMP_REQUEUE_PI — no capabilities, root, or namespaces are required.\nUI:N - The bug is triggered entirely by the attacker's own threads and syscalls; no action by any other user is needed.\nS:U - The corruption is confined to kernel memory within the same security authority; it is a standard local kernel privilege issue with no cross-boundary (VM/IOMMU) escape.\nC:H - The dangling pi_blocked_on pointer and rbtree dequeue under the wrong pi_lock give a use-after-free over reclaimed stack memory, which can be leveraged to read controlled kernel memory contents.\nI:H - The UAF and unsynchronized rbtree manipulation provide a write primitive into kernel data structures, enabling memory corruption exploitable for control-flow hijacking and privilege escalation.\nA:H - The dangling pointer dereference and PI-chain corruption readily cause kernel oops/panic, so availability impact is high."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:28:22.054Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.6.140"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.12.86"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.18.27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"7.0.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/07/08/12"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-07-08T22:22:10.721Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-22T03:55:28.271423Z","id":"CVE-2026-43499","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","type":"CWE","lang":"en","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-26T19:01:26.917Z"}},{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 TM MFP - GNU/Linux subsystem","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:19:29.734Z"},"x_adpType":"supplier"}]}}}