{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53240","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-06-09T07:44:35.393Z","datePublished":"2026-06-25T08:39:35.809Z","dateUpdated":"2026-08-05T12:34:26.772Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:34:26.772Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: fix use-after-free on first_skb in __input_process_payload\n\n__input_process_payload() stores first_skb into xtfs->ra_newskb under\ndrop_lock when starting partial reassembly, then unlocks and breaks out\nof the processing loop. The post-loop check reads xtfs->ra_newskb\nwithout the lock to decide whether first_skb is still owned:\n\n    if (first_skb && first_iplen && !defer && first_skb != xtfs->ra_newskb)\n\nBetween spin_unlock and this read, a concurrent CPU running\niptfs_reassem_cont() (or the drop_timer hrtimer) can complete\nreassembly, NULL xtfs->ra_newskb, and free the skb. The check then\nevaluates first_skb != NULL as true, and pskb_trim/ip_summed/consume_skb\noperate on the freed skb — a use-after-free in skbuff_head_cache.\n\nReplace the unlocked read with a local bool that records whether\nfirst_skb was handed to the reassembly state in the current call. The\nflag is set after the existing spin_unlock, before the break, using the\npointer equality that is stable at that point (first_skb == skb iff\nfirst_skb was stored in ra_newskb)."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable IPTFS parser is reached from the network receive path through xfrm4/xfrm6 ESP handling, xfrm_input, and iptfs_input on an inbound IPTFS SA. A reasonable high-impact deployment is an internet-reachable IPsec/IPTFS gateway processing remote peer traffic.\nAC:L - The bug is a use-after-free race after first_skb is handed to reassembly, and the attacker can drive the needed fragmented/reordered IPTFS packets and concurrent continuation processing. There is no condition beyond the attacker’s control once valid IPTFS ESP traffic reaches the SA.\nPR:L - Unauthenticated packets are rejected by XFRM/ESP state lookup, replay, and crypto verification before IPTFS parsing, so a remote attacker needs valid SA access or credentials. Locally, creating the IPTFS SA requires CAP_NET_ADMIN in a network namespace, which is reachable as low privilege via user namespaces.\nUI:N - No victim user action is required after the vulnerable SA is present; packet receipt alone triggers the path. The attacker sends crafted traffic to the configured endpoint.\nS:U - The impact is kernel memory corruption within the same host kernel security authority. This is not a VM escape, IOMMU bypass, or other cross-scope boundary.\nC:H - This is a use-after-free of an sk_buff from skbuff_head_cache, and freed object reuse can expose kernel memory or support stronger disclosure primitives. Under the required guidance, UAF memory corruption warrants high confidentiality impact.\nI:H - The stale sk_buff is subsequently used by pskb_trim, field writes, and freeing paths, giving a plausible route to heap corruption and control-flow or data corruption. Under the required guidance, UAF memory corruption warrants high integrity impact.\nA:H - The stale sk_buff access can corrupt kernel heap state or crash in packet processing/freeing paths. A kernel oops, panic, or repeatable crash is high availability impact."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_iptfs.c"],"versions":[{"version":"3f3339885fb343b7b42d7c34717108ce07da24ae","lessThan":"8d9a79fbf5172d9c4c0146057af2360913265a11","status":"affected","versionType":"git"},{"version":"3f3339885fb343b7b42d7c34717108ce07da24ae","lessThan":"ff2ee35b6ce5fa8a8e24ea50b15733d5c8780198","status":"affected","versionType":"git"},{"version":"3f3339885fb343b7b42d7c34717108ce07da24ae","lessThan":"eb48730bb827d1550401a5d391903f9d90b493c8","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_iptfs.c"],"versions":[{"version":"6.14","status":"affected"},{"version":"0","lessThan":"6.14","status":"unaffected","versionType":"semver"},{"version":"6.18.36","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.13","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.18.36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.0.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/8d9a79fbf5172d9c4c0146057af2360913265a11"},{"url":"https://git.kernel.org/stable/c/ff2ee35b6ce5fa8a8e24ea50b15733d5c8780198"},{"url":"https://git.kernel.org/stable/c/eb48730bb827d1550401a5d391903f9d90b493c8"}],"title":"xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload","x_generator":{"engine":"bippy-1.2.0"}}}}