CVE Catalog

CVE-2026-53012

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.19%

8th percentile - higher than 8% of all known CVEs

Summary

In the Linux kernel, a vulnerability occurs when an IPv6 nexthop is replaced with an IPv4 nexthop without updating the has_v4 flag in all groups containing this nexthop. This allows IPv6 routes to reference groups with only AF_INET members, causing a NULL pointer dereference and system panic.

Risk Assessment

The organization risks system panic during IPv6 routing, leading to network service disruptions and potential availability loss.

Recommendation

Immediately update the Linux kernel to a version containing the fix (commit that adds nh_group_v4_update call when changing from AF_INET6 to AF_INET).

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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

Vulnerability data from NVD (NIST) · CISA KEV · EPSS