CVE-2026-23304: Linux kernel · ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in d542e2ac7f9e288d49735be0775611547ca4e0ee : update Linux kernel when convenient.
Data as of 5 Nov 2026, 21:49 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, 2026-11-05.
- Patch
- Available – fixed in d542e2ac7f9e288d49735be0775611547ca4e0ee, ae88c8256547b63980770a9ea7be73a15900d27e, a73fe9f4ae84a239d5b2686f47a58c158aee2eb4 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 25 Mar 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 5 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: ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu() l3mdev_master_dev_rcu() can return NULL when the slave device is being un-slaved from a VRF. All other callers deal with this, but we lost the fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu() with commit 4832c30d5458 ("net: ipv6: put host and anycast routes on device with address"). KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418) Call Trace: ip6_pol_route (net/ipv6/route.c:2318) fib6_rule_lookup (net/ipv6/fib6_rules.c:115) ip6_route_output_flags (net/ipv6/route.c:2607) vrf_process_v6_outbound (drivers/net/vrf.c:437) I was tempted to rework the un-slaving code to clear the flag first and insert synchronize_rcu() before we remove the upper. But looks like the explicit fallback to loopback_dev is an established pattern. And I guess avoiding the synchronize_rcu() is nice, too.
References
- git.kernel.org/stable/c/d542e2ac7f9e288d49735be0775611547ca4e0ee (opens in a new tab)
- git.kernel.org/stable/c/a73fe9f4ae84a239d5b2686f47a58c158aee2eb4 (opens in a new tab)
- git.kernel.org/stable/c/4a48fe59f29f673a3d042d679f26629a9c3e29d4 (opens in a new tab)
- git.kernel.org/stable/c/581800298313c9fd75e94985e6d37d21b7e35d34 (opens in a new tab)
- git.kernel.org/stable/c/3310fc11fc47387d1dd4759b0bc961643ea11c7f (opens in a new tab)
- git.kernel.org/stable/c/0b5a7826020706057cc5a9d9009e667027f221ee (opens in a new tab)
- git.kernel.org/stable/c/ae88c8256547b63980770a9ea7be73a15900d27e (opens in a new tab)
- git.kernel.org/stable/c/2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (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)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)