CVE-2026-52998
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk39th percentile — higher than 39% of all known CVEs
Summary
In the Linux kernel, a vulnerability was found in the netfilter nfnetlink_osf module, where the nf_osf_ttl() function accessed the network interface pointer (skb->dev) without validation, potentially causing a NULL pointer dereference. The TTL check logic also relied on incorrect assumptions about local subnet addresses, which could fail in containerized or virtual switching environments.
Risk Assessment
The risk includes potential kernel panic or incorrect packet filtering, which could lead to network service disruption or bypass of security rules.
Recommendation
Immediately update the Linux kernel to a version containing the fix that removes unsafe device dereferences and replaces the TTL check logic with a safe switch statement.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check The nf_osf_ttl() function accessed skb->dev to perform a local interface address lookup without verifying that the device pointer was valid. Additionally, the implementation utilized an in_dev_for_each_ifa_rcu loop to match the packet source address against local interface addresses. It assumed that packets from the same subnet should not see a decrement on the initial TTL. A packet might appear it is from the same subnet but it actually isn't especially in modern environments with containers and virtual switching. Remove the device dereference and interface loop. Replace the logic with a switch statement that evaluates the TTL according to the ttl_check.