eventpoll: fix ep_remove struct eventpoll / struct file UAF
In the Linux kernel, the following vulnerability has been resolved: eventpoll: fix ep_remove struct eventpoll / struct file UAF ep_remove() (via ep_remove_file()) cleared file->f_ep under file->f_lock but then kept using @file inside the critical section (is_file_epoll(), hlist_del_rcu() through the head, spin_unlock). A concurrent __fput() taking the eventpoll_release() fastpath in that window observed the transient NULL, skipped eventpoll_release_file() and ran to f_op->release / file_free(). For the epoll-watches-epoll case, f_op->release is ep_eventpoll_release() -> ep_clear_and_put() -> ep_free(), which kfree()s the watched struct eventpoll. Its embedded ->refs hlist_head is exactly where epi->fllink.pprev points, so the subsequent hlist_del_rcu()'s "*pprev = next" scribbles into freed kmalloc-192 memory. In addition, struct file is SLAB_TYPESAFE_BY_RCU, so the slot backing @file could be recycled by alloc_empty_file() -- reinitializing f_lock and f_ep -- while ep_remove() is still nominally inside that lock. The upshot is an attacker-controllable kmem_cache_free() against the wrong slab cache. Pin @file via epi_fget() at the top of ep_remove() and gate the critical section on the pin succeeding. With the pin held @file cannot reach refcount zero, which holds __fput() off and transitively keeps the watched struct eventpoll alive across the hlist_del_rcu() and the f_lock use, closing both UAFs. If the pin fails @file has already reached refcount zero and its __fput() is i
CVE-2026-46242
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-46242
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "f2451def095c1743adcfcb0cb5dadc86034e162a",
"lessThan": "a10fbbe74e1c743beb1bb312109366667461df8a",
"versionType": "git"
},
{
"status": "affected",
"version": "a1f93804449d13f97dabd4b996817de4bf1ed67a",
"lessThan": "3e1144d2515d28e4312e663ea05eac203101491d",
"versionType": "git"
},
{
"status": "affected",
"version": "58c9b016e12855286370dfb704c08498edbc857a",
"lessThan": "2de4db145b2992da496fea6c51f9839be678ae24",
"versionType": "git"
},
{
"status": "affected",
"version": "58c9b016e12855286370dfb704c08498edbc857a",
"lessThan": "9324de74a3a59b9fde9b62ee45ebaa71458ba2e5",
"versionType": "git"
},
{
"status": "affected",
"version": "58c9b016e12855286370dfb704c08498edbc857a",
"lessThan": "ef4ca02e95363e78977ca04340d44fe3b4b2b81f",
"versionType": "git"
},
{
"status": "affected",
"version": "58c9b016e12855286370dfb704c08498edbc857a",
"lessThan": "ced39b6a8062bac5c18a1c3df85634107eb8664a",
"versionType": "git"
},
{
"status": "affected",
"version": "58c9b016e12855286370dfb704c08498edbc857a",
"lessThan": "a6dc643c69311677c574a0f17a3f4d66a5f3744b",
"versionType": "git"
},
{
"status": "affected",
"version": "5.15.209",
"lessThan": "5.15.222",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.1.175",
"lessThan": "6.1.178",
"versionType": "semver"
}
],
"programFiles": [
"fs/eventpoll.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.4"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.4",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.15.222",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.144",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.95",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.33",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.10",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/eventpoll.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-46242
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40161 · Revision 1
- Added to Heist Feed
- Publisher date