---
cve: "CVE-2026-43139"
severity: "HIGH"
cvss: 8.6
epss: "38%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-05-06 12:16:31"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-06T11:03:07+02:00"
---

# CVE-2026-43139

> 8.6 HIGH

## Beschreibung

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

xfrm6: fix uninitialized saddr in xfrm6_get_saddr()

xfrm6_get_saddr() does not check the return value of
ipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find a suitable
source address (returns -EADDRNOTAVAIL), saddr->in6 is left
uninitialized, but xfrm6_get_saddr() still returns 0 (success).

This causes the caller xfrm_tmpl_resolve_one() to use the uninitialized
address in xfrm_state_find(), triggering KMSAN warning:

=====================================================
BUG: KMSAN: uninit-value in xfrm_state_find+0x2424/0xa940
 xfrm_state_find+0x2424/0xa940
 xfrm_resolve_and_create_bundle+0x906/0x5a20
 xfrm_lookup_with_ifid+0xcc0/0x3770
 xfrm_lookup_route+0x63/0x2b0
 ip_route_output_flow+0x1ce/0x270
 udp_sendmsg+0x2ce1/0x3400
 inet_sendmsg+0x1ef/0x2a0
 __sock_sendmsg+0x278/0x3d0
 __sys_sendto+0x593/0x720
 __x64_sys_sendto+0x130/0x200
 x64_sys_call+0x332b/0x3e70
 do_syscall_64+0xd3/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable tmp.i.i created at:
 xfrm_resolve_and_create_bundle+0x3e3/0x5a20
 xfrm_lookup_with_ifid+0xcc0/0x3770
=====================================================

Fix by checking the return value of ipv6_dev_get_saddr() and propagating
the error.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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 | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.10.252
- Kernel ≥ 5.15.202
- Kernel ≥ 6.1.165
- Kernel ≥ 6.6.128
- Kernel ≥ 6.12.75
- Kernel ≥ 6.18.16
- Kernel ≥ 6.19.6

## Referenzen

- <https://git.kernel.org/stable/c/4f28141786e1fe884ce42a5197ba9beed540f0ea>
- <https://git.kernel.org/stable/c/6535867673bf301d52aa00593a4d1d18cc3922fa>
- <https://git.kernel.org/stable/c/eb2ee15290af14c60b45cf2b73f5687d1d077d9b>
- <https://git.kernel.org/stable/c/719918fc88df6da023dfff370cd965151a5afd7f>
- <https://git.kernel.org/stable/c/dc0abce055134cb83b0d981d31ceb20dda419787>
- <https://git.kernel.org/stable/c/c7221e7bd8fc2ef38a0b27be580d9d202281306b>
- <https://git.kernel.org/stable/c/3dcd1664ac15eee6a690daec7c4ffc59190406f7>
- <https://git.kernel.org/stable/c/1799d8abeabc68ec05679292aaf6cba93b343c05>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-43139) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_