CVE-2026-46116

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Source
https://cve.org/CVERecord?id=CVE-2026-46116
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-46116.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-46116
Downstream
Related
Published
2026-05-28T09:35:30Z
Modified
2026-09-10T03:30:41Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete
Details

In the Linux kernel, the following vulnerability has been resolved:

xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete

KASAN reproduces a slab-use-after-free in __xfrm_state_delete()'s hlist_del_rcu calls under syzkaller load on linux-6.12.y stable (reproduced on 6.12.47, also reachable via the same code path on torvalds/master and on the ipsec tree). Nine unique signatures cluster in the xfrm_state lifecycle, the load-bearing one being:

BUG: KASAN: slab-use-after-free in __hlist_del include/linux/list.h:990 [inline] BUG: KASAN: slab-use-after-free in hlist_del_rcu include/linux/rculist.h:516 [inline] BUG: KASAN: slab-use-after-free in __xfrm_state_delete net/xfrm/xfrm_state.c Write of size 8 at addr ffff8881198bcb70 by task kworker/u8:9/435

Workqueue: netns cleanup_net Call Trace: __hlist_del / hlist_del_rcu __xfrm_state_delete xfrm_state_delete xfrm_state_flush xfrm_state_fini ops_exit_list cleanup_net

The other observed signatures hit the same slab object from __xfrm_state_lookup, xfrm_alloc_spi, __xfrm_state_insert and an OOB write variant of __xfrm_state_delete, all on the byseq/byspi hash chains.

__xfrm_state_delete() guards its byseq and byspi unhashes with value-based predicates:

if (x->km.seq)
	hlist_del_rcu(&x->byseq);
if (x->id.spi)
	hlist_del_rcu(&x->byspi);

while everywhere else in the file (e.g. state_cache, state_cache_input) the safer hlist_unhashed() check is used. xfrm_alloc_spi() sets x->id.spi = newspi inside xfrm_state_lock and then immediately inserts into byspi, but a path that observes x->id.spi != 0 outside of xfrm_state_lock can still skip-or-hit the byspi unhash inconsistently with whether x is actually on the list. The same holds for x->km.seq versus byseq, and the bydst/bysrc unhashes have no predicate at all, so a second __xfrm_state_delete() on the same object writes through LIST_POISON pprev.

The defensive change here:

  • Use hlist_del_init_rcu() instead of hlist_del_rcu() on bydst, bysrc, byseq and byspi so a second deletion is a no-op rather than a write through LIST_POISON pprev. The byseq/byspi nodes are already initialised in xfrm_state_alloc().
  • Test hlist_unhashed() rather than the value predicate for byseq/byspi, so the unhash decision tracks list state rather than mutable scalar fields.

Empirical verification: applied this patch on top of v6.12.47, rebuilt, and re-ran the same syzkaller harness for 1h16m on a previously-crashy configuration that produced ~100 hits each of slab-use-after-free Read in xfrm_alloc_spi / Read in __xfrm_state_lookup / Write in __xfrm_state_delete. After the patch, 7.1M execs across 32 VMs at ~1550 exec/sec produced zero xfrm_state UAF/OOB hits. /proc/slabinfo confirms the xfrm_state slab is actively allocated and freed during the run (~143 KiB resident), so the fuzzer is still exercising those code paths -- they just no longer crash.

Reproduction:

  • Linux 6.12.47 x86_64 + KASAN_GENERIC + KASAN_INLINE + KCOV
  • syzkaller @ 746545b8b1e4c3a128db8652b340d3df90ce61db
  • 32 QEMU/KVM VMs x 2 vCPU on AWS c5.metal bare metal
  • 9 unique signatures collected in ~9h, all within xfrm_state lifecycle
Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46116.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
7b4dc3600e4877178ba94c7fbf7e520421378aa6
Fixed
6b4dc3181b4bfc5f5fc33ab33b1dc6e15759f4b6
Fixed
3943fcad7694a7d0b15aeabe7d3cc2a2eb8e92e8
Fixed
2c617848ae6e4f07a3e397f604208c293bbecacc
Fixed
b4a53add2fa8f1b5aa17d4c5686c320785fab182
Fixed
26edb0a3c99f9d958c212be68b21f1221614dcf0
Fixed
4980162de555cb838f1a189ce7d2cbf5d2e7b050
Fixed
a2e2d08fb070fab4947447171f1c4e3ca5a188e5
Fixed
14acf9652e5690de3c7486c6db5fb8dafd0a32a3

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-46116.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
2.6.19
Fixed
5.10.261
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.210
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.176
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.140
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.88
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.18.30
Type
ECOSYSTEM
Events
Introduced
6.19.0
Fixed
7.0.7

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-46116.json"