---
cve: "CVE-2026-89789"
severity: "HIGH"
cvss: 7.8
epss: "21%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-16 09:17:09"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-18T16:24:13+02:00"
---

# CVE-2026-89789

> 7.8 HIGH

## Beschreibung

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

gtp: add synchronize_net() in gtp_newlink() error path to prevent use-after-free

gtp_newlink()'s error path frees tid_hash and addr_hash without
waiting for an RCU grace period after clearing sk_user_data. A
concurrent gtp_encap_recv() in softirq may still hold the gtp_dev
pointer obtained via rcu_dereference_sk_user_data() and access the
freed memory.

  BUG: KASAN: slab-use-after-free in gtp0_pdp_find+0x1f6/0x200 (gtp.c:152)
  Call Trace:
   
   gtp0_pdp_find+0x1f6/0x200
   gtp_encap_recv+0x527/0x24b0
   udp_queue_rcv_one_skb+0x75f/0xc10

Add synchronize_net() before the kfree calls in out_hashtable, which
covers all error paths from both gtp_encap_enable() and
gtp_create_sockets().

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- Kernel ≥ 5.10.270
- Kernel ≥ 5.15.221
- Kernel ≥ 6.1.188
- Kernel ≥ 6.6.157
- Kernel ≥ 6.12.110
- Kernel ≥ 6.18.52
- Kernel ≥ 7.2.6

## Referenzen

- <https://git.kernel.org/stable/c/fcafb2b1430824bae4258c01a439ec97ca0c6973>
- <https://git.kernel.org/stable/c/3ca3da5c305caa873ddb81e8c6b118143f6dd3d1>
- <https://git.kernel.org/stable/c/6f815c2fb6ab20385f81c353cdad0ea3b88132af>
- <https://git.kernel.org/stable/c/e3b9aa0773abd5d4ed90be41ce5306c146d5b09e>
- <https://git.kernel.org/stable/c/fd8396cfecbd904468c71362f08aaa25f96d5337>
- <https://git.kernel.org/stable/c/7677eb2cbf2cc7446de474c01a6b06277c0051e5>
- <https://git.kernel.org/stable/c/8d85498016a5bb56339734a14c276209fa65bafc>
- <https://git.kernel.org/stable/c/d989e22ae9802c52c56ad4284d0caf26696cf6ae>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-89789) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_