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VulnerabilityPublished Updated

CVE-2026-43029: Linux kernel · mptcp: fix soft lockup in mptcp_recvmsg()

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 7.5 High · fixed in 6.8.0-1035.38 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 25% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.8.0-1035.38, 7.0.0-1006.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 the Ubuntu to 6.8.0-1035.38 (linux-nvidia-tegra package) or 7.0.0-1006.6 (linux-nvidia package).

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1003.3 – 7.0.0-1008.8
4 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-nvidiapkg:deb/ubuntu/linux-nvidia?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1006.6
Fixed in
  • 7.0.0-1006.6
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threatsAffected
  • 6.14.0-15.15 – 6.17.0-40.40
20 affected builds
Fixed in–
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1005.5 – 6.17.0-1019.19
17 affected builds
Fixed in–
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1004.4 – 6.17.0-1020.20
16 affected builds
Fixed in–
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied to affected Linux kernel versions. After applying the update, a system reboot is required to complete remediation. Users should update to the fixed kernel package versions provided by their distribution vendor, such as the Ubuntu kernel updates referenced in the advisory. No additional mitigation is required beyond applying the official fix and rebooting.

Description

A soft lockup vulnerability in the Linux kernel's mptcp_recvmsg() function was identified and fixed. The issue occurs when receiving data with MSG_PEEK and MSG_WAITALL flags, causing the socket buffer not to be removed from the receive queue. This leads to the kernel function sk_wait_data() continuously finding data available and never waiting, resulting in a CPU soft lockup. The fix tracks the last peeked socket buffer to allow proper waiting behavior and prevent infinite loops. This vulnerability affects multiple Linux kernel versions, including various Ubuntu kernel packages. A patch is available to address this issue.

References

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