CVE Catalog

CVE-2026-74657

Low risk· EPSS 7%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

7th percentile - higher than 7% of all known CVEs

Summary

In the Linux kernel, fib_nlmsg_size() incorrectly estimated nexthop space assuming every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which is dumped as RTA_VIA, leading to undersized skb allocation and -EMSGSIZE errors, and with panic_on_warn set, a kernel panic.

Risk Assessment

Incorrect route notifications can cause system crashes (kernel panic) when panic_on_warn is enabled, leading to service disruption.

Recommendation

Apply the kernel patch that accounts for the actual nexthop dump layout in fib_nlmsg_size(), including IPv6 gateways as RTA_VIA and appropriate RTA_MULTIPATH and RTA_FLOW cases.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops fib_nlmsg_size() still estimates nexthop space as if every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA. As a result, route notifications can allocate an skb that is too small. fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With panic_on_warn set, this becomes a kernel panic. Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is actually present.

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