CVE-2026-74704: Linux kernel · net/sched: sch_cake: drop WARN_ON(1) for malformed packets in ACK filter
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.2 High · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 38% 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 +27
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 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 that removes the unnecessary WARN_ON condition in the sch_cake ACK filter code. Applying the official Linux kernel update that includes this fix will mitigate the issue. No additional action is required beyond updating to a fixed kernel version.
Description
A vulnerability in the Linux kernel's sch_cake ACK filter allows malformed IP packets to trigger a WARN_ON(1) condition. This can cause excessive kernel log warnings or a kernel panic if panic_on_warn is enabled. The issue arises because the ACK filter parsing code triggers a warning on malformed packets, but the packet is already skipped correctly, making the warning unnecessary. This vulnerability has been addressed by removing the WARN_ON to prevent these side effects.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74704 (opens in a new tab)
- git.kernel.org/stable/c/0c4882bff34558d8d53fb04c3e96da5c327c7dc8 (opens in a new tab)
- git.kernel.org/stable/c/2504a76e5c0694e14e15562730e1339f2d9f9458 (opens in a new tab)
- git.kernel.org/stable/c/2a33516f9ef59ad11844d4fc152f889449b5daf3 (opens in a new tab)
- git.kernel.org/stable/c/a1ae353d8355407c1bea971d1c1af5e7f242bb7d (opens in a new tab)
- git.kernel.org/stable/c/a4b52612004a5639c4bfc30ba93ba414b8326e2a (opens in a new tab)
- git.kernel.org/stable/c/ae1b2f8e21a41e7c7e75511bea0c4ccc59ec1bd3 (opens in a new tab)
- git.kernel.org/stable/c/c1693b7844a6c06d31a565e5a494948034dfd235 (opens in a new tab)
- git.kernel.org/stable/c/cd2f1d9fe8a507c2dc86ad326fe221f121c47734 (opens in a new tab)
- ubuntu.com/security/CVE-2026-74704 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74704 (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-8886-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-2 (opens in a new tab)