---
cve: "CVE-2026-53175"
severity: "CRITICAL"
cvss: 9.8
epss: "31%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-06-25 09:16:34"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-07T09:47:44+02:00"
---

# CVE-2026-53175

> 9.8 CRITICAL

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.12.94
- Kernel ≥ 6.18.36
- Kernel ≥ 7.0.13

## Referenzen

- <https://git.kernel.org/stable/c/0e823ca0e7391630784ae7dd0981b7ad170a93d9>
- <https://git.kernel.org/stable/c/c22599cc90e1cd5f8129c8670bd68a02ff7177b4>
- <https://git.kernel.org/stable/c/89b909e9704587bfecc1aab1d37e98faee03b9f9>
- <https://git.kernel.org/stable/c/010c3313a4d178dc2d3ce958d2e5cb055e2864c1>
- <https://git.kernel.org/stable/c/32594b09854970d7ba83eb2dc8c69a2edd158c8e>
- <https://access.redhat.com/security/cve/CVE-2026-53175>
- <https://bugzilla.redhat.com/show_bug.cgi?id=2492840>
- <https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53175.json>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-53175) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_