CVE-2026-43139: Linux kernel · xfrm6: fix uninitialized saddr in xfrm6_get_saddr()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 8.6 High · fixed in eb2ee15290af14c60b45cf2b73f5687d1d077d9b : patch Linux kernel soon.
Data as of 26 Oct 2026, 15:59 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in eb2ee15290af14c60b45cf2b73f5687d1d077d9b, dc0abce055134cb83b0d981d31ceb20dda419787, c7221e7bd8fc2ef38a0b27be580d9d202281306b +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 6 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
AI-suggested
A fix is available and has been applied in multiple commits identified by their hashes. Users running Linux kernel version 2.6.19 should update to a fixed version containing these commits to remediate the issue. No additional mitigation steps are indicated by the vendor advisory.
Description
CVE-2026-43139 is a high-severity vulnerability in the Linux kernel affecting version 2.6.19. It involves the xfrm6_get_saddr() function failing to check the return value of ipv6_dev_get_saddr(), which can leave the source address uninitialized. This uninitialized value is then used by subsequent functions, causing a kernel memory sanitizer (KMSAN) warning and potentially leading to undefined behavior or system instability. The issue has been fixed by adding proper error checking and propagation of the failure from ipv6_dev_get_saddr().
References
- git.kernel.org/stable/c/4f28141786e1fe884ce42a5197ba9beed540f0ea (opens in a new tab)
- git.kernel.org/stable/c/6535867673bf301d52aa00593a4d1d18cc3922fa (opens in a new tab)
- git.kernel.org/stable/c/eb2ee15290af14c60b45cf2b73f5687d1d077d9b (opens in a new tab)
- git.kernel.org/stable/c/719918fc88df6da023dfff370cd965151a5afd7f (opens in a new tab)
- git.kernel.org/stable/c/dc0abce055134cb83b0d981d31ceb20dda419787 (opens in a new tab)
- git.kernel.org/stable/c/c7221e7bd8fc2ef38a0b27be580d9d202281306b (opens in a new tab)
- git.kernel.org/stable/c/3dcd1664ac15eee6a690daec7c4ffc59190406f7 (opens in a new tab)
- git.kernel.org/stable/c/1799d8abeabc68ec05679292aaf6cba93b343c05 (opens in a new tab)