CVE-2026-31586

{"id": "CVE-2026-31586", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-31586", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T15:10:59.894304Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 1.8}]}, "affected": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "affectedData": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "23acef4156c260e8598397a1a2e8b3a23e919893", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "1bd36e93b542d9dd020190c6607c6a3663405195", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "740ba1ebb223f137ff088ab74d533a13f9167bd8", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "115a5266749dcde7fe4127e8623d19c752088f69", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "dfc8292a1d6782c76b626315605e0585a5a18447", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "ea3af09eb87d8f8708c66747fcf1a2762902e839", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "50879a3c1faf06e661090015d59e2127255cff27", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "67cb119d32f35e32acd0393bbeb318b2bb1fdafe", "versionType": "git"}, {"status": "affected", "version": "59b57717fff8b562825d9d25e0180ad7e8048ca9", "lessThan": "8f5857be99f1ed1fa80991c72449541f634626ee", "versionType": "git"}], "programFiles": ["mm/backing-dev.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "4.19"}, {"status": "unaffected", "version": "0", "lessThan": "4.19", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.258", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.209", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.175", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.136", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.83", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.24", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "6.19.14", "versionType": "semver", "lessThanOrEqual": "6.19.*"}, {"status": "unaffected", "version": "7.0.1", "versionType": "semver", "lessThanOrEqual": "7.0.*"}, {"status": "unaffected", "version": "7.1", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["mm/backing-dev.c"], "defaultStatus": "affected"}]}, {"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "affectedData": [{"vendor": "Siemens", "product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem", "versions": [{"status": "affected", "version": "0", "lessThan": "*", "versionType": "custom"}], "defaultStatus": "unknown"}]}], "published": "2026-04-24T15:16:33.393", "references": [{"url": "https://git.kernel.org/stable/c/115a5266749dcde7fe4127e8623d19c752088f69", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/1bd36e93b542d9dd020190c6607c6a3663405195", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/23acef4156c260e8598397a1a2e8b3a23e919893", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/50879a3c1faf06e661090015d59e2127255cff27", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/67cb119d32f35e32acd0393bbeb318b2bb1fdafe", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/740ba1ebb223f137ff088ab74d533a13f9167bd8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/8f5857be99f1ed1fa80991c72449541f634626ee", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/dfc8292a1d6782c76b626315605e0585a5a18447", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/ea3af09eb87d8f8708c66747fcf1a2762902e839", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://cert-portal.siemens.com/productcert/html/ssa-784472.html", "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-416"}]}, {"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "description": [{"lang": "en", "value": "CWE-416"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: blk-cgroup: fix use-after-free in cgwb_release_workfn()\n\ncgwb_release_workfn() calls css_put(wb->blkcg_css) and then later accesses\nwb->blkcg_css again via blkcg_unpin_online(). If css_put() drops the last\nreference, the blkcg can be freed asynchronously (css_free_rwork_fn ->\nblkcg_css_free -> kfree) before blkcg_unpin_online() dereferences the\npointer to access blkcg->online_pin, resulting in a use-after-free:\n\n BUG: KASAN: slab-use-after-free in blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)\n Write of size 4 at addr ff11000117aa6160 by task kworker/71:1/531\n Workqueue: cgwb_release cgwb_release_workfn\n Call Trace:\n <TASK>\n blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)\n cgwb_release_workfn (mm/backing-dev.c:629)\n process_scheduled_works (kernel/workqueue.c:3278 kernel/workqueue.c:3385)\n\n Freed by task 1016:\n kfree (./include/linux/kasan.h:235 mm/slub.c:2689 mm/slub.c:6246 mm/slub.c:6561)\n css_free_rwork_fn (kernel/cgroup/cgroup.c:5542)\n process_scheduled_works (kernel/workqueue.c:3302 kernel/workqueue.c:3385)\n\n** Stack based on commit 66672af7a095 (\"Add linux-next specific files\nfor 20260410\")\n\nI am seeing this crash sporadically in Meta fleet across multiple kernel\nversions. A full reproducer is available at:\nhttps://github.com/leitao/debug/blob/main/reproducers/repro_blkcg_uaf.sh\n\n(The race window is narrow. To make it easily reproducible, inject a\nmsleep(100) between css_put() and blkcg_unpin_online() in\ncgwb_release_workfn(). With that delay and a KASAN-enabled kernel, the\nreproducer triggers the splat reliably in less than a second.)\n\nFix this by moving blkcg_unpin_online() before css_put(), so the\ncgwb's CSS reference keeps the blkcg alive while blkcg_unpin_online()\naccesses it."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmm: blk-cgroup: corregir uso despu\u00e9s de liberaci\u00f3n en cgwb_release_workfn()\n\ncgwb_release_workfn() llama a css_put(wb -> blkcg_css) y luego accede a wb -> blkcg_css de nuevo a trav\u00e9s de blkcg_unpin_online(). Si css_put() libera la \u00faltima referencia, el blkcg puede ser liberado asincr\u00f3nicamente (css_free_rwork_fn -> blkcg_css_free -> kfree) antes de que blkcg_unpin_online() desreferencie el puntero para acceder a blkcg -> online_pin, resultando en un uso despu\u00e9s de liberaci\u00f3n:\n\n BUG: KASAN: slab-uso-despu\u00e9s-de-liberaci\u00f3n en blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)\n Escritura de tama\u00f1o 4 en la direcci\u00f3n ff11000117aa6160 por la tarea kworker/71:1/531\n Cola de trabajo: cgwb_release cgwb_release_workfn\n Rastro de llamada:\n [TAREA]\n blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)\n cgwb_release_workfn (mm/backing-dev.c:629)\n process_scheduled_works (kernel/workqueue.c:3278 kernel/workqueue.c:3385)\n\n Liberado por la tarea 1016:\n kfree (./include/linux/kasan.h:235 mm/slub.c:2689 mm/slub.c:6246 mm/slub.c:6561)\n css_free_rwork_fn (kernel/cgroup/cgroup.c:5542)\n process_scheduled_works (kernel/workqueue.c:3302 kernel/workqueue.c:3385)\n\n** Pila basada en el commit 66672af7a095 (\u2019Add linux-next specific files for 20260410\u2019)\n\nEstoy viendo este fallo espor\u00e1dicamente en la flota de Meta en m\u00faltiples versiones del kernel. Un reproductor completo est\u00e1 disponible en:\nhttps://github.com/leitao/debug/blob/main/reproducers/repro_blkcg_uaf.sh\n\n(La ventana de carrera es estrecha. Para que sea f\u00e1cilmente reproducible, inyecte un msleep(100) entre css_put() y blkcg_unpin_online() en cgwb_release_workfn(). Con ese retraso y un kernel habilitado para KASAN, el reproductor activa el splat de forma fiable en menos de un segundo.)\n\nCorrija esto moviendo blkcg_unpin_online() antes de css_put(), para que la referencia CSS del cgwb mantenga el blkcg activo mientras blkcg_unpin_online() accede a \u00e9l."}], "lastModified": "2026-11-11T23:10:00.263", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C65C5FE4-6002-4BBA-98A9-87D1F99A643F", "versionEndExcluding": "6.6.136", "versionStartIncluding": "4.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8", "versionEndExcluding": "6.12.83", "versionStartIncluding": "6.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555", "versionEndExcluding": "6.18.24", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB", "versionEndExcluding": "6.19.14", "versionStartIncluding": "6.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "9B5888AB-7403-4335-89E4-21CC0B48366A", "versionEndExcluding": "7.0.1", "versionStartIncluding": "7.0"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}