net/sched: act_ct: fix sk_buff leak when the header checks reject a packet

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74621
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:34 UTC
Updated2026-08-23 13:16:47 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: fix sk_buff leak when the header checks reject a packet tcf_ct_handle_fragments() runs its header sanity checks before handing anything to the defragmentation engine: if (family == NFPROTO_IPV4) err = tcf_ct_ipv4_is_fragment(skb, &frag); else err = tcf_ct_ipv6_is_fragment(skb, &frag); if (err || !frag) return err; tcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM; tcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of them frees or queues the skb, so on that path the caller still owns it. tcf_ct_act() however funnels every non-zero return into the ownership-transfer exit: err = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag); if (err) goto out_frag; ... out_frag: if (err != -EINPROGRESS) tcf_action_inc_drop_qstats(&c->common); return TC_ACT_CONSUMED; TC_ACT_CONSUMED means the action took ownership of the skb, so no caller frees it - sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for that verdict. The skb is therefore orphaned: one sk_buff plus its data buffer is leaked per malformed packet, unbounded. Note the drop counter is already incremented for these errors, so the statistics claim a drop that never happens. Three different ownership states reach out_frag: today - the skb may be queued by the defrag engine (-EINPROGRESS), already freed by nf_ct_handle_fragments(), or still owned by us. Tell the caller which of those it is, and free the packet ourselves in the last case, which restores the TC_ACT_SHOT behaviour that predated the Fixes: commit. Reproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6 header with nexthdr = 0 (hop-by-hop) and nothing after it, on a clsact ingress chain with "action ct". kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet; with this patch it reports none.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 172ba7d46c202e679f3ccb10264c67416aaeb1c4 b5dbecc2016e1692fd1c2532af9c41ba729cb747 git Not specified
CNA Linux Linux affected 0b5b831122fc3789fff75be433ba3e4dd7b779d4 23e97d594ddd0153020c506d5041048fbde1beb4 git Not specified
CNA Linux Linux affected 73f7da5fd124f2cda9161e2e46114915e6e82e97 737873a59905a54ca0d2d127ef882f3f88bf4379 git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 47d99828591d0fe8be4b9c8992ff3b8e47968db9 git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 b47bb899e04b5407c5a63fe88d4b6676586a6e84 git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 439d3e404f9d5e515911cc8132cde198b337c19e git Not specified
CNA Linux Linux affected 3f14b377d01d8357eba032b4cabc8c1149b458b6 8a7ed561671aa6a911a2de99e59ef670a4d0b1df git Not specified
CNA Linux Linux affected f5346df0591d10bc948761ca854b1fae6d2ef441 git Not specified
CNA Linux Linux affected 5.15.148 5.15.217 semver Not specified
CNA Linux Linux affected 6.1.75 6.1.184 semver Not specified
CNA Linux Linux affected 6.6.14 6.6.152 semver Not specified
CNA Linux Linux affected 6.7.2 6.8 semver Not specified
CNA Linux Linux affected 6.8 Not specified
CNA Linux Linux unaffected 6.8 semver Not specified
CNA Linux Linux unaffected 5.15.217 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.184 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b47bb899e04b5407c5a63fe88d4b6676586a6e84 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/439d3e404f9d5e515911cc8132cde198b337c19e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b5dbecc2016e1692fd1c2532af9c41ba729cb747 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/47d99828591d0fe8be4b9c8992ff3b8e47968db9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/737873a59905a54ca0d2d127ef882f3f88bf4379 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/23e97d594ddd0153020c506d5041048fbde1beb4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8a7ed561671aa6a911a2de99e59ef670a4d0b1df 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report