In the Linux kernel, the following vulnerability has been resolved:
inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush
On netns teardown, fqdir_pre_exit() walks the fqdir rhashtable and
flushes every fragment queue that is not yet complete using
inet_frag_queue_flush(). That helper frees all the skbs queued on the
fragment queue but does not set INET_FRAG_COMPLETE, and leaves
q->fragments_tail and q->last_run_head pointing at the freed skbs.
The queue itself stays in the rhashtable.
fqdir_pre_exit() first lowers high_thresh to 0 to stop new queue lookups,
but it cannot stop a fragment that already obtained the queue through
inet_frag_find() earlier and stalled just before taking the queue lock.
Once that fragment resumes after the flush and takes the queue lock,
it passes the INET_FRAG_COMPLETE check and then dereferences the freed
fragments_tail. inet_frag_queue_insert() reads FRAG_CB() and ->len of
that pointer and, on the append path, writes ->next_frag, causing a
slab use-after-free. IPv6, nf_conntrack_reasm6 and 6lowpan reassembly
share the same flush path and are affected as well.
Reset rb_fragments, fragments_tail and last_run_head in
inet_frag_queue_flush() so a flushed queue no longer points at the
freed skbs. A fragment that resumes after the flush and takes the
queue lock then finds an empty queue and starts a new run instead of
dereferencing the freed fragments_tail. ip_frag_reinit() already
performed this reset after its own flush, so drop the now duplicate
code there.
References
Configurations
No configuration.
History
30 Jun 2026, 03:20
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| References |
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28 Jun 2026, 08:16
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| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 9.8 |
25 Jun 2026, 09:16
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| New CVE |
Information
Published : 2026-06-25 09:16
Updated : 2026-06-30 14:44
NVD link : CVE-2026-53175
Mitre link : CVE-2026-53175
CVE.ORG link : CVE-2026-53175
JSON object : View
Products Affected
No product.
CWE
No CWE.