{ "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" } } } }