---
cve: "CVE-2026-31533"
severity: "CRITICAL"
cvss: 9.8
epss: "39%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-04-23 18:16:26"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-19T01:38:01+02:00"
---

# CVE-2026-31533

> 9.8 CRITICAL

## Beschreibung

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

net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption

The -EBUSY handling in tls_do_encryption(), introduced by commit
859054147318 ("net: tls: handle backlogging of crypto requests"), has
a use-after-free due to double cleanup of encrypt_pending and the
scatterlist entry.

When crypto_aead_encrypt() returns -EBUSY, the request is enqueued to
the cryptd backlog and the async callback tls_encrypt_done() will be
invoked upon completion. That callback unconditionally restores the
scatterlist entry (sge->offset, sge->length) and decrements
ctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an
error, the synchronous error path in tls_do_encryption() performs the
same cleanup again, double-decrementing encrypt_pending and
double-restoring the scatterlist.

The double-decrement corrupts the encrypt_pending sentinel (initialized
to 1), making tls_encrypt_async_wait() permanently skip the wait for
pending async callbacks. A subsequent sendmsg can then free the
tls_rec via bpf_exec_tx_verdict() while a cryptd callback is still
pending, resulting in a use-after-free when the callback fires on the
freed record.

Fix this by skipping the synchronous cleanup when the -EBUSY async
wait returns an error, since the callback has already handled
encrypt_pending and sge restoration.

## 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 ≥ 5.15.203
- Kernel ≥ 6.1.169
- Kernel ≥ 6.6.135
- Kernel ≥ 6.12.82
- Kernel ≥ 6.18.23
- Kernel ≥ 6.19.13

## Referenzen

- <https://git.kernel.org/stable/c/414fc5e5a5aff776c150f1b86770e0a25a35df3a>
- <https://git.kernel.org/stable/c/02f3ecadb23558bbe068e6504118f1b712d4ece0>
- <https://git.kernel.org/stable/c/0e43e0a3c94044acc74b8e0927c27972eb5a59e8>
- <https://git.kernel.org/stable/c/aa9facde6c5005205874c37db3fd25799d741baf>
- <https://git.kernel.org/stable/c/5d70eb25b41e9b010828cd12818b06a0c3b04412>
- <https://git.kernel.org/stable/c/2694d408b0e595024e0fc1d64ff9db0358580f74>
- <https://git.kernel.org/stable/c/a9b8b18364fffce4c451e6f6fd218fa4ab646705>
- <https://cert-portal.siemens.com/productcert/html/ssa-019113.html>
- <https://cert-portal.siemens.com/productcert/html/ssa-082556.html>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-31533) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_