CVE-2026-74282: Linux kernel · tipc: prevent snt_unacked underflow on CONN_ACK
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +42
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 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 |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| 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. The fix validates the acknowledgment count in CONN_ACK messages and drops invalid messages, preventing the underflow and denial of service. Users should update to patched kernel versions as provided by their Linux distribution or vendor.
Description
A vulnerability in the Linux kernel's TIPC protocol implementation allowed a peer to cause an underflow in the send counter by sending an oversized connection acknowledgment. This could wedge the send side of a TIPC connection, resulting in a denial of service by starving the connection of further transmissions. The issue has been fixed by validating the acknowledgment count and dropping invalid messages.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74282 (opens in a new tab)
- git.kernel.org/stable/c/1e2c956745777e6ffdee7f30da5935741c03ee1e (opens in a new tab)
- git.kernel.org/stable/c/3388145d258cf2c4c98278e3987296007d30672e (opens in a new tab)
- git.kernel.org/stable/c/3cfa3d8e0dc167850edeb5bf5a07757db83fd54e (opens in a new tab)
- git.kernel.org/stable/c/47ed873e4ceda34098bd46d8e96b4bb13cad3a04 (opens in a new tab)
- git.kernel.org/stable/c/67e55b054bf8025658dc0e255057f2a6236416bd (opens in a new tab)
- git.kernel.org/stable/c/96f91b8ae1a489b3eca137e7acf42cf985fb8939 (opens in a new tab)
- git.kernel.org/stable/c/ab3e10b44ba5411779aac7afd2477917dd77750f (opens in a new tab)
- git.kernel.org/stable/c/b44bebdd32c9ff66ee2aebfc317ced44bedd9335 (opens in a new tab)
- ubuntu.com/security/CVE-2026-74282 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74282 (opens in a new tab)
- git.kernel.org/linus/ab3e10b44ba5411779aac7afd2477917dd77750f (opens in a new tab)
- ubuntu.com/security/notices/USN-8876-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8889-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8886-1 (opens in a new tab)