CVE-2026-43080: Linux kernel · l2tp: Drop large packets with UDP encap
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc : update Linux kernel when convenient.
Data as of 6 Nov 2026, 16:18 UTC
Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-06.
- Patch
- Available – fixed in f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc, ebe560ea5f54134279356703e73b7f867c89db13, c2994fd24997ed63d713c03313f863645adb4d6c +5
Exploitation evidence
Disclosed: evidence found.
CVE published 6 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 6 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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AI-suggested
A fix is available and has been applied in the Linux kernel. The patch adds an overflow check that drops oversized packets before they are transmitted, preventing the UDP length field overflow. Users should update to a Linux kernel version that includes this fix. No additional mitigation steps are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's L2TP implementation allows oversized PPPoL2TP packets with UDP encapsulation to overflow the 16-bit UDP length field. This overflow causes the UDP length to be truncated, potentially leading to malformed packets being sent. The issue was detected by syzbot and fixed by adding an overflow check that drops oversized packets before transmission.
References
- git.kernel.org/stable/c/02d787fd0922c71c0264449fe82d35983613e4e5 (opens in a new tab)
- git.kernel.org/stable/c/c2994fd24997ed63d713c03313f863645adb4d6c (opens in a new tab)
- git.kernel.org/stable/c/a42452db035577e150ffd9adf98c56fef9fb9408 (opens in a new tab)
- git.kernel.org/stable/c/9ccce02d501335f59a02f26c878c5e095b16302f (opens in a new tab)
- git.kernel.org/stable/c/77c1489398c85a844f90205f5e76fd6bc8bb4089 (opens in a new tab)
- git.kernel.org/stable/c/86534c97abd6365a9a021fd767a2023e63c44469 (opens in a new tab)
- git.kernel.org/stable/c/f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc (opens in a new tab)
- git.kernel.org/stable/c/ebe560ea5f54134279356703e73b7f867c89db13 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)