CVE-2026-53012: Linux kernel · nexthop: fix IPv6 route referencing IPv4 nexthop
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in ceffe81a0be92afc0cd1340bc8ca46559cce9bb4 : update Linux kernel when convenient.
Data as of 6 Nov 2026, 16:49 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-06.
- Patch
- Available – fixed in ceffe81a0be92afc0cd1340bc8ca46559cce9bb4, b3b7e850e1541f0520c4a12ec884255c30427ff6, ad85961004fd4bd2f31209ac4b07612c6cefb9e7 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 24 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 6 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: nexthop: fix IPv6 route referencing IPv4 nexthop syzbot reported a panic [1] [2]. When an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag of all groups containing this nexthop is not updated. This is because nh_group_v4_update is only called when replacing AF_INET to AF_INET6, but the reverse direction (AF_INET6 to AF_INET) is missed. This allows a stale has_v4=false to bypass fib6_check_nexthop, causing IPv6 routes to be attached to groups that effectively contain only AF_INET members. Subsequent route lookups then call nexthop_fib6_nh() which returns NULL for the AF_INET member, leading to a NULL pointer dereference. Fix by calling nh_group_v4_update whenever the family changes, not just AF_INET to AF_INET6. Reproducer: # AF_INET6 blackhole ip -6 nexthop add id 1 blackhole # group with has_v4=false ip nexthop add id 100 group 1 # replace with AF_INET (no -6), has_v4 stays false ip nexthop replace id 1 blackhole # pass stale has_v4 check ip -6 route add 2001:db8::/64 nhid 100 # panic ping -6 2001:db8::1 [1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0 [2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3
References
- git.kernel.org/stable/c/ceffe81a0be92afc0cd1340bc8ca46559cce9bb4 (opens in a new tab)
- git.kernel.org/stable/c/9c2d6770a5f4545a307eb66979bef7656a34d621 (opens in a new tab)
- git.kernel.org/stable/c/6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8 (opens in a new tab)
- git.kernel.org/stable/c/aaac3bed034239e1d75732211d9b05f30b0b4f35 (opens in a new tab)
- git.kernel.org/stable/c/ad85961004fd4bd2f31209ac4b07612c6cefb9e7 (opens in a new tab)
- git.kernel.org/stable/c/613c8f4a501421dd258b07ea614205d4e16ec845 (opens in a new tab)
- git.kernel.org/stable/c/b3b7e850e1541f0520c4a12ec884255c30427ff6 (opens in a new tab)
- git.kernel.org/stable/c/29c95185ba32b621fbc3800fb86e7dc3edf5c2be (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)