CVE-2026-72248
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk9th percentile - higher than 9% of all known CVEs
Summary
In the Linux kernel, the netfilter flowtable module has a vulnerability that causes a crash during IPIP tunnel transmission with direct xmit. The lack of dst_entry leads to invalid dst usage and can trigger a crash.
Risk Assessment
Using IPIP tunnel with direct xmit (e.g., on a bridge device) can lead to a system crash in the tunnel transmit path.
Recommendation
Apply a Linux kernel update containing the fix that moves dst_cache and dst_cookie to shared fields and makes them available for direct xmit mode.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: support IPIP tunnel with direct xmit The combination of IPIP tunnel with direct xmit, eg. bridge device, breaks because no dst_entry is provided to check the skb headroom and to set the iph->frag_off field. This leads to invalid dst usage and can trigger a crash in the tunnel transmit path. Fix this by moving dst_cache and dst_cookie out of the runtime union so that they can be shared by neighbour, xfrm, and direct tunnel flows. For FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve route state in these shared fields and release it through the common dst release path. Since dst_entry is now available to the three supported xmit modes and dst_release() already deals with NULL dst, remove the xmit type check in nft_flow_dst_release(). Moreover, skip the check if the dst entry is NULL in nf_flow_dst_check() which is now the case for the direct xmit case. Based on patch from Rein Wei <[email protected]>.