{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-74621", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-74621", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-08-22T15:32:04.990Z", "updatedAt": "2026-10-16T19:06:02.607Z", "importedAt": "2026-10-24T01:58:30.346Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "net/sched: act_ct: fix sk_buff leak when the header checks reject a packet", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: fix sk_buff leak when the header checks reject a packet\n\ntcf_ct_handle_fragments() runs its header sanity checks before handing\nanything to the defragmentation engine:\n\n\tif (family == NFPROTO_IPV4)\n\t\terr = tcf_ct_ipv4_is_fragment(skb, &frag);\n\telse\n\t\terr = tcf_ct_ipv6_is_fragment(skb, &frag);\n\tif (err || !frag)\n\t\treturn err;\n\ntcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM;\ntcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of\nthem frees or queues the skb, so on that path the caller still owns it.\n\ntcf_ct_act() however funnels every non-zero return into the\nownership-transfer exit:\n\n\terr = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag);\n\tif (err)\n\t\tgoto out_frag;\n\t...\nout_frag:\n\tif (err != -EINPROGRESS)\n\t\ttcf_action_inc_drop_qstats(&c->common);\n\treturn TC_ACT_CONSUMED;\n\nTC_ACT_CONSUMED means the action took ownership of the skb, so no caller\nfrees it - sch_handle_ingress(), sch_handle_egress() and\ntcf_qevent_handle() all deliberately skip the free for that verdict. The\nskb is therefore orphaned: one sk_buff plus its data buffer is leaked per\nmalformed packet, unbounded. Note the drop counter is already incremented\nfor these errors, so the statistics claim a drop that never happens.\n\nThree different ownership states reach out_frag: today - the skb may be\nqueued by the defrag engine (-EINPROGRESS), already freed by\nnf_ct_handle_fragments(), or still owned by us. Tell the caller which of\nthose it is, and free the packet ourselves in the last case, which\nrestores the TC_ACT_SHOT behaviour that predated the Fixes: commit.\n\nReproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6\nheader with nexthdr = 0 (hop-by-hop) and nothing after it, on a\nclsact ingress chain with \"action ct\". kmemleak reports one leaked\n232-byte skbuff_head_cache object plus its 704-byte data buffer per\npacket; with this patch it reports none.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "172ba7d46c202e679f3ccb10264c67416aaeb1c4", "status": "affected", "versionType": "git", "lessThan": "b5dbecc2016e1692fd1c2532af9c41ba729cb747" }, { "version": "0b5b831122fc3789fff75be433ba3e4dd7b779d4", "status": "affected", "versionType": "git", "lessThan": "23e97d594ddd0153020c506d5041048fbde1beb4" }, { "version": "73f7da5fd124f2cda9161e2e46114915e6e82e97", "status": "affected", "versionType": "git", "lessThan": "737873a59905a54ca0d2d127ef882f3f88bf4379" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "status": "affected", "versionType": "git", "lessThan": "47d99828591d0fe8be4b9c8992ff3b8e47968db9" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "status": "affected", "versionType": "git", "lessThan": "b47bb899e04b5407c5a63fe88d4b6676586a6e84" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "status": "affected", "versionType": "git", "lessThan": "439d3e404f9d5e515911cc8132cde198b337c19e" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "status": "affected", "versionType": "git", "lessThan": "8a7ed561671aa6a911a2de99e59ef670a4d0b1df" }, { "version": "f5346df0591d10bc948761ca854b1fae6d2ef441", "status": "affected", "versionType": "git" }, { "version": "5.15.148", "status": "affected", "versionType": "semver", "lessThan": "5.15.217" }, { "version": "6.1.75", "status": "affected", "versionType": "semver", "lessThan": "6.1.184" }, { "version": "6.6.14", "status": "affected", "versionType": "semver", "lessThan": "6.6.152" }, { "version": "6.7.2", "status": "affected", "versionType": "semver", "lessThan": "6.8" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.8" }, { "version": "5.15.217", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.184", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.152", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.104", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.45", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.1.9", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }