{"id":"CVE-2026-53240","summary":"xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload","details":"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-\u003era_newskb under\ndrop_lock when starting partial reassembly, then unlocks and breaks out\nof the processing loop. The post-loop check reads xtfs-\u003era_newskb\nwithout the lock to decide whether first_skb is still owned:\n\n    if (first_skb && first_iplen && !defer && first_skb != xtfs-\u003era_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-\u003era_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).","modified":"2026-07-10T03:54:28.913755170Z","published":"2026-06-25T08:39:35.809Z","related":["CGA-w6j4-j49w-39fv"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53240.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/8d9a79fbf5172d9c4c0146057af2360913265a11"},{"type":"WEB","url":"https://git.kernel.org/stable/c/eb48730bb827d1550401a5d391903f9d90b493c8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ff2ee35b6ce5fa8a8e24ea50b15733d5c8780198"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53240.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53240"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3f3339885fb343b7b42d7c34717108ce07da24ae"},{"fixed":"8d9a79fbf5172d9c4c0146057af2360913265a11"},{"fixed":"ff2ee35b6ce5fa8a8e24ea50b15733d5c8780198"},{"fixed":"eb48730bb827d1550401a5d391903f9d90b493c8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53240.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.14.0"},{"fixed":"6.18.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53240.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}