# CVE-2026-89757: mm/mglru: fix and remove redundant unevictable folio handling CVE-2026-89757 is fixed in 20 products on 1 platform, first by DEBIAN-CVE-2026-89757, released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-89757 - Priority: Routine - CVSS: 3.6 (Low) - EPSS: 0.0021 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 11, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-89757 ## Description In the Linux kernel, the following vulnerability has been resolved: mm/mglru: fix and remove redundant unevictable folio handling sort_folio() has a shortcut for moving folios that are no longer evictable but are still sitting on a generation list. However, this shortcut is buggy. It does not follow the PG_lru usage convention, and it has a more serious issue. Unevictable folios are not threaded on lists[LRU_UNEVICTABLE], so that folio->lru can be reused to hold folio->mlock_count (see the comment in lruvec_init()). Hence lruvec_add_folio() skips the list_add() for them, and every other place that turns a folio unevictable initialises mlock_count explicitly: lru_add() sets it to 0, __mlock_folio() and __mlock_new_folio() set it to !!folio_test_mlocked(folio). sort_folio() sets nothing, and the lru_gen_del_folio() right above it may have already poisoned folio->lru via list_del(), so mlock_count ends up aliasing LIST_POISON2, which reads as 0x122, i.e. 290. The result is user visible. On munlock, __munlock_folio() decrements that bogus count, finds it still non-zero and bails out before clearing PG_mlocked, so the folio remains unevictable and the Mlocked accounting stays inflated until the folio is freed. The shortcut also touches the LRU flags in the wrong order. It calls lru_gen_del_folio() while PG_lru is still set, so a concurrent folio_test_clear_lru() (e.g. compaction, folio_isolate_lru()) can succeed on a folio that has already been taken off the generation list, which may lead to unexpected behavior. So fix it by isolating them as common folios and letting the generic shrink path cull them. This matches the classical LRU behavior, and there should be no visible effect on the generic eviction or isolation behavior. There is no performance concern either, such a folio goes through this once, and then it is off the generation lists for good. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel-livepatch-6.18.51-120.162 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-89757](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89757.md) | Sep 23, 2026 | | Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89757](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89757.md) | Sep 23, 2026 | | Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.51-120.162.amzn2023 | [ALAS2023-2026-3187](https://patchblox.com/security/data/fix/linux/alas2023-2026-3187.md) | Nov 7, 2026 | --- Data as of 2026-11-07T12:40:37Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo