{"id":"CVE-2026-89752","title":"mm: memcg: stop reclaim when a limit update is superseded","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: memcg: stop reclaim when a limit update is superseded\n\nkernfs serializes file operations only per open file, so separate open\nfiles can update the same memory.high …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-367"],"vendor":"Linux","product":"Linux","affected":["Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < ebf762a393630d1582645be3f0fc22a674eb9122","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 4ea0617b9e46d26c0a3e5af00308ea1931cc545d","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 5c6f87d33733d96fba66ea4e78cd8b24b4d60a49","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 8bf21ad3657305e28deafd9ef16a121407496bc3","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 39ec1e4183a718f448b2e9de681dcbdda18fce42","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 95d87030cae7764805aa7c621c52871139297cb0","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < aab391074de96ed601eeca32daef9a8507d436d9","Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 9477820c63cbf4d97114238f3d1ff10dfd6bee3f","Linux 0ccab5b139971a2a3f48df24d1ee8be2dbf84042","Linux 97729c37439040ec07807f0dbb71ea60ccbafd27","Linux >= 4.4.7 < 4.5","Linux >= 4.5.1 < 4.6","Linux 4.6"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:52:05.993Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89752","references":[{"url":"https://git.kernel.org/stable/c/ebf762a393630d1582645be3f0fc22a674eb9122"},{"url":"https://git.kernel.org/stable/c/4ea0617b9e46d26c0a3e5af00308ea1931cc545d"},{"url":"https://git.kernel.org/stable/c/5c6f87d33733d96fba66ea4e78cd8b24b4d60a49"},{"url":"https://git.kernel.org/stable/c/8bf21ad3657305e28deafd9ef16a121407496bc3"},{"url":"https://git.kernel.org/stable/c/39ec1e4183a718f448b2e9de681dcbdda18fce42"},{"url":"https://git.kernel.org/stable/c/95d87030cae7764805aa7c621c52871139297cb0"},{"url":"https://git.kernel.org/stable/c/aab391074de96ed601eeca32daef9a8507d436d9"},{"url":"https://git.kernel.org/stable/c/9477820c63cbf4d97114238f3d1ff10dfd6bee3f"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89752.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89752"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532245"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89752"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89752"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89752.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00177,"epssPercentile":0.07146,"ingestedAt":"2026-09-14T15:23:07.448Z","slug":"CVE-2026-89752","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nmm: memcg: stop reclaim when a limit update is superseded\n\nkernfs serializes file operations only per open file, so separate open\nfiles can update the same memory.high or memory.max file concurrently. \nBoth handlers store the new limit before synchronous reclaim, but continue\nto use the writer's local target in the reclaim loop.  If another writer\nraises or removes the limit, the first writer can continue reclaiming\ntoward a stale target.\n\nFor memory.max, this can leave the writer looping indefinitely once\nreclaim retries are exhausted.  The OOM path sees sufficient margin under\nthe current limit and returns true without killing, while the writer still\ncompares usage against its stale target and records another OOM event.\n\nCheck the current limit at the start of each reclaim iteration and stop if\nit no longer matches the writer's target.\n\nReproducer:\n\nPopulate a cgroup with anonymous memory and disable swapping.  Lower\nmemory.max from one open file, then restore it to \"max\" through another\nopen file after the new limit becomes visible.\n\nWithout the patch, the first writer remains blocked and repeatedly\nincrements the OOM event counter.  With the patch, it returns normally.\n\nThis was not motivated by a reported production workload.  We found it\nthrough automated randomized testing for our cgroup observability work\nand reduced it to the reproducer above.\n\n## Affected\n\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < ebf762a393630d1582645be3f0fc22a674eb9122`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 4ea0617b9e46d26c0a3e5af00308ea1931cc545d`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 5c6f87d33733d96fba66ea4e78cd8b24b4d60a49`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 8bf21ad3657305e28deafd9ef16a121407496bc3`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 39ec1e4183a718f448b2e9de681dcbdda18fce42`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 95d87030cae7764805aa7c621c52871139297cb0`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < aab391074de96ed601eeca32daef9a8507d436d9`\n- `Linux >= b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f < 9477820c63cbf4d97114238f3d1ff10dfd6bee3f`\n- `Linux 0ccab5b139971a2a3f48df24d1ee8be2dbf84042`\n- `Linux 97729c37439040ec07807f0dbb71ea60ccbafd27`\n- `Linux >= 4.4.7 < 4.5`\n- `Linux >= 4.5.1 < 4.6`\n- `Linux 4.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89752.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":208943,"id":"CVE-2026-89752","ts":1790062297520,"field":"cvss","old":"4.1","new":"5.5"},{"seq":204037,"id":"CVE-2026-89752","ts":1789490231148,"field":"cvss","old":null,"new":"4.1"},{"seq":204036,"id":"CVE-2026-89752","ts":1789490231148,"field":"severity","old":"none","new":"medium"},{"seq":147486,"id":"CVE-2026-89752","ts":1789270211097,"field":"cvss","old":null,"new":"4.1"},{"seq":147485,"id":"CVE-2026-89752","ts":1789270211097,"field":"severity","old":"none","new":"medium"},{"seq":109242,"id":"CVE-2026-89752","ts":1789183731113,"field":"cvss","old":null,"new":"4.1"},{"seq":109241,"id":"CVE-2026-89752","ts":1789183731113,"field":"severity","old":"none","new":"medium"}]}