CVE-2026-53240
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk34th percentile — higher than 34% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's xfrm IPsec module in the __input_process_payload function. The issue occurs when first_skb is stored in xtfs->ra_newskb without a lock, allowing another thread to free it, leading to use of freed memory.
Risk Assessment
An attacker could remotely trigger a kernel panic or potentially escalate privileges by sending crafted IPsec packets.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit addressing the issue). Monitor distributions for the patch release.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload __input_process_payload() stores first_skb into xtfs->ra_newskb under drop_lock when starting partial reassembly, then unlocks and breaks out of the processing loop. The post-loop check reads xtfs->ra_newskb without the lock to decide whether first_skb is still owned: if (first_skb && first_iplen && !defer && first_skb != xtfs->ra_newskb) Between spin_unlock and this read, a concurrent CPU running iptfs_reassem_cont() (or the drop_timer hrtimer) can complete reassembly, NULL xtfs->ra_newskb, and free the skb. The check then evaluates first_skb != NULL as true, and pskb_trim/ip_summed/consume_skb operate on the freed skb — a use-after-free in skbuff_head_cache. Replace the unlocked read with a local bool that records whether first_skb was handed to the reassembly state in the current call. The flag is set after the existing spin_unlock, before the break, using the pointer equality that is stable at that point (first_skb == skb iff first_skb was stored in ra_newskb).