CVE-2024-26752: Linux kernel · l2tp: pass correct message length to ip6_append_data
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.4.0-1126.136~18.04.1 : update Linux kernel when convenient.
Data as of 28 Oct 2026, 10:59 UTC
- Patch
- Available – fixed in 5.4.0-1126.136~18.04.1, 5.4.0-1131.138~18.04.1, 5.4.0-1130.139~18.04.1 +56
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Apr 2024
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.
Patches and advisories
- ubuntu.com/security/notices/USN-6820-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6828-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6820-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6831-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-6867-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6871-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6892-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6919-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu Pro Realtime 24.04 LTSlinux-raspi-realtimepkg:deb/ubuntu/linux-raspi-realtime?arch=source&distro=realtime/nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSlinux-allwinner-5.19pkg:deb/ubuntu/linux-allwinner-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSlinux-aws-5.19pkg:deb/ubuntu/linux-aws-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-aws-6.2pkg:deb/ubuntu/linux-aws-6.2?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: l2tp: pass correct message length to ip6_append_data l2tp_ip6_sendmsg needs to avoid accounting for the transport header twice when splicing more data into an already partially-occupied skbuff. To manage this, we check whether the skbuff contains data using skb_queue_empty when deciding how much data to append using ip6_append_data. However, the code which performed the calculation was incorrect: ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0; ...due to C operator precedence, this ends up setting ulen to transhdrlen for messages with a non-zero length, which results in corrupted packets on the wire. Add parentheses to correct the calculation in line with the original intent.
References
- ubuntu.com/security/CVE-2024-26752 (opens in a new tab)
- git.kernel.org/linus/359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79 (opens in a new tab)
- git.kernel.org/stable/c/4c3ce64bc9d36ca9164dd6c77ff144c121011aae (opens in a new tab)
- git.kernel.org/stable/c/c1d3a84a67db910ce28a871273c992c3d7f9efb5 (opens in a new tab)
- git.kernel.org/stable/c/dcb4d14268595065c85dc5528056713928e17243 (opens in a new tab)
- git.kernel.org/stable/c/0da15a70395182ee8cb75716baf00dddc0bea38d (opens in a new tab)
- git.kernel.org/stable/c/13cd1daeea848614e585b2c6ecc11ca9c8ab2500 (opens in a new tab)
- git.kernel.org/stable/c/804bd8650a3a2bf3432375f8c97d5049d845ce56 (opens in a new tab)
- git.kernel.org/stable/c/83340c66b498e49353530e41542500fc8a4782d6 (opens in a new tab)
- git.kernel.org/stable/c/359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2024-26752 (opens in a new tab)
- ubuntu.com/security/notices/USN-6820-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6828-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6820-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6831-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6821-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-6867-1 (opens in a new tab)