CVE-2026-74597: Linux kernel · ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 45% 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:H/I:H/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 and should be applied to affected Linux kernel versions to clear the skb2->cb[] metadata before processing the inner IPv6 packet. The vendor advisory from Ubuntu confirms that this issue has been fixed in updated kernel packages. Users should update their Linux kernel to the fixed versions as provided by their distribution. No additional mitigation is required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's ip6_tunnel component was resolved that involved improper handling of metadata in cloned IPv6 ICMP error packets. The issue allowed stale metadata from an outer IPv6 packet to be reused when processing an inner quoted IPv6 packet, potentially causing memory corruption. This flaw could be triggered by a malformed inner destination-options header leading to corruption of skb_shared_info. A patch is available that clears the relevant metadata before processing the inner packet to prevent this issue.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74597 (opens in a new tab)
- git.kernel.org/stable/c/0dadb0620ab65949a8bc2439dd28ea3c942fe87d (opens in a new tab)
- git.kernel.org/stable/c/44fe898df302e91c5ee5acbc71ffa74e78e6c183 (opens in a new tab)
- git.kernel.org/stable/c/484134e1eb07d700a73b1e4bbf3fb503e299be60 (opens in a new tab)
- git.kernel.org/stable/c/4eb15c465337b18f44716c499cd6ad63eee0ad54 (opens in a new tab)
- git.kernel.org/stable/c/64e41736a26f37ab6215bc2e6df125df05aceb08 (opens in a new tab)
- git.kernel.org/stable/c/b6816536a2990c0db44a26130a03e40b441e829b (opens in a new tab)
- git.kernel.org/stable/c/f803c086399da277b5d0ff36a107d0f162751800 (opens in a new tab)
- git.kernel.org/stable/c/fbf40faa0414b753212494ad197542002e66ed9e (opens in a new tab)
- ubuntu.com/security/CVE-2026-74597 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74597 (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)