CVE-2026-89757
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()).
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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.
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 2/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-89757",
"cveTags": [],
"metrics": {},
"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": "ac35a490237446b71e3b4b782b1596967edd0aa8",
"lessThan": "54a58d6656dd403b686b247f0bad8507cbfb45df",
"versionType": "git"
},
{
"status": "affected",
"version": "ac35a490237446b71e3b4b782b1596967edd0aa8",
"lessThan": "15d3a2a71c8bf7333d019d249ee33669e69e4275",
"versionType": "git"
},
{
"status": "affected",
"version": "ac35a490237446b71e3b4b782b1596967edd0aa8",
"lessThan": "f7e698e326b239a91ea15844817551921209e826",
"versionType": "git"
}
],
"programFiles": [
"mm/vmscan.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.1",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.51",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"mm/vmscan.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-11T20:20:06.767",
"references": [
{
"url": "https://git.kernel.org/stable/c/15d3a2a71c8bf7333d019d249ee33669e69e4275",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/54a58d6656dd403b686b247f0bad8507cbfb45df",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f7e698e326b239a91ea15844817551921209e826",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mglru: fix and remove redundant unevictable folio handling\n\nsort_folio() has a shortcut for moving folios that are no longer evictable\nbut are still sitting on a generation list. However, this shortcut is\nbuggy. It does not follow the PG_lru usage convention, and it has a more\nserious issue.\n\nUnevictable folios are not threaded on lists[LRU_UNEVICTABLE], so that\nfolio->lru can be reused to hold folio->mlock_count (see the comment in\nlruvec_init()). Hence lruvec_add_folio() skips the list_add() for them,\nand every other place that turns a folio unevictable initialises\nmlock_count explicitly: lru_add() sets it to 0, __mlock_folio() and\n__mlock_new_folio() set it to !!folio_test_mlocked(folio). sort_folio()\nsets nothing, and the lru_gen_del_folio() right above it may have already\npoisoned folio->lru via list_del(), so mlock_count ends up aliasing\nLIST_POISON2, which reads as 0x122, i.e. 290. The result is user\nvisible. On munlock, __munlock_folio() decrements that bogus count, finds\nit still non-zero and bails out before clearing PG_mlocked, so the folio\nremains unevictable and the Mlocked accounting stays inflated until the\nfolio is freed.\n\nThe shortcut also touches the LRU flags in the wrong order. It calls\nlru_gen_del_folio() while PG_lru is still set, so a concurrent\nfolio_test_clear_lru() (e.g. compaction, folio_isolate_lru()) can succeed\non a folio that has already been taken off the generation list, which may\nlead to unexpected behavior.\n\nSo fix it by isolating them as common folios and letting the generic\nshrink path cull them. This matches the classical LRU behavior, and there\nshould be no visible effect on the generic eviction or isolation behavior.\n\nThere is no performance concern either, such a folio goes through this\nonce, and then it is off the generation lists for good."
}
],
"lastModified": "2026-09-11T20:20:06.767",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}