CVE-2024-40931: Linux kernel · mptcp: ensure snd_una is properly initialized on connect
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.15.0-1069.75~20.04.1 : update Linux kernel when convenient.
Data as of 12 Nov 2026, 19:04 UTC
- Patch
- Available – fixed in 5.15.0-1069.75~20.04.1, 5.15.0-1072.81~20.04.1, 5.15.0-1068.76~20.04.1 +48
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 12 Jul 2024
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 12 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-6999-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7004-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7005-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7008-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7005-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7009-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7019-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6999-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7029-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=nobleOther 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: mptcp: ensure snd_una is properly initialized on connect This is strictly related to commit fb7a0d334894 ("mptcp: ensure snd_nxt is properly initialized on connect"). It turns out that syzkaller can trigger the retransmit after fallback and before processing any other incoming packet - so that snd_una is still left uninitialized. Address the issue explicitly initializing snd_una together with snd_nxt and write_seq.
References
- ubuntu.com/security/CVE-2024-40931 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2024-40931 (opens in a new tab)
- git.kernel.org/linus/8031b58c3a9b1db3ef68b3bd749fbee2e1e1aaa3 (opens in a new tab)
- git.kernel.org/stable/c/208cd22ef5e57f82d38ec11c1a1703f9401d6dde (opens in a new tab)
- git.kernel.org/stable/c/7b9c7fc8600b64a86e4b47b2d190bba380267726 (opens in a new tab)
- git.kernel.org/stable/c/f03c46eabb3a67bd2993e237ab5517f00a5f1813 (opens in a new tab)
- git.kernel.org/stable/c/f1f0a46f8bb8890b90ab7194f0a0c8fe2a3fb57f (opens in a new tab)
- git.kernel.org/stable/c/ef473bf1dd7e8dd08bcc04b9e2d1bfed69a0a7ce (opens in a new tab)
- git.kernel.org/stable/c/8031b58c3a9b1db3ef68b3bd749fbee2e1e1aaa3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6999-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7004-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7005-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7008-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7005-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7009-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7019-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6999-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-3 (opens in a new tab)