CVE-2026-23300: Linux kernel · net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · patch available : update Linux kernel when convenient.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
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 25 Mar 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?arch=source&distro=questingOther 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 corrects the classification logic to ensure proper initialization of nexthop objects, preventing the kernel panic. Users should update to the fixed kernel versions as per the vendor advisory. No additional mitigation actions are required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's IPv6 networking code could cause a kernel panic when an IPv4 route references a standalone IPv6 nexthop object associated with the loopback device. This occurs due to improper handling of the nexthop object's classification, leading to a null pointer dereference. The issue has been fixed by adjusting the classification logic to properly allocate necessary resources, preventing the crash.
References
- ubuntu.com/security/CVE-2026-23300 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23300 (opens in a new tab)
- git.kernel.org/linus/21ec92774d1536f71bdc90b0e3d052eff99cf093 (opens in a new tab)
- git.kernel.org/stable/c/21ec92774d1536f71bdc90b0e3d052eff99cf093 (opens in a new tab)
- git.kernel.org/stable/c/8650db85b4259d2885d2a80fbc2317ce24194133 (opens in a new tab)
- git.kernel.org/stable/c/b299121e7453d23faddf464087dff513a495b4fc (opens in a new tab)
- git.kernel.org/stable/c/b3b5a037d520afe3d5276e653bc0ff516bbda34c (opens in a new tab)
- git.kernel.org/stable/c/b5062fc2150614c9ea8a611c2e0cb6e047ebfa3a (opens in a new tab)
- git.kernel.org/stable/c/f7c9f8e3607440fe39300efbaf46cf7b5eecb23f (opens in a new tab)
- ubuntu.com/security/notices/USN-8567-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8596-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8597-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-2 (opens in a new tab)