Answer in brief
CVE-2026-74621 records a High severity (CVSS 7.5) vulnerability in net/sched: act_ct: fix sk_buff leak when the header checks reject a packet. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=73f7da5fd124f2cda9161e2e46114915e6e82e97 <737873a59905a54ca0d2d127ef882f3f88bf4379 || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <47d99828591d0fe8be4b9c8992ff3b8e47968db9 || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <b47bb899e04b5407c5a63fe88d4b6676586a6e84 || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <439d3e404f9d5e515911cc8132cde198b337c19e || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <8a7ed561671aa6a911a2de99e59ef670a4d0b1df || 172ba7d46c202e679f3ccb10264c67416aaeb1c4 || 0b5b831122fc3789fff75be433ba3e4dd7b779d4 || f5346df0591d10bc948761ca854b1fae6d2ef441 || >=6.6.14 <6.6.152 || >=5.15.148 <5.16 || >=6.1.75 <6.2 || >=6.7.2 <6.8 | 737873a59905a54ca0d2d127ef882f3f88bf4379, 47d99828591d0fe8be4b9c8992ff3b8e47968db9, b47bb899e04b5407c5a63fe88d4b6676586a6e84, 439d3e404f9d5e515911cc8132cde198b337c19e, 8a7ed561671aa6a911a2de99e59ef670a4d0b1df, 6.6.152, 5.16, 6.2, 6.8 |
| Linux/Linuxgeneric | 6.8 | Not reported |
| Linux/Linuxgeneric | >=172ba7d46c202e679f3ccb10264c67416aaeb1c4 <b5dbecc2016e1692fd1c2532af9c41ba729cb747 || >=0b5b831122fc3789fff75be433ba3e4dd7b779d4 <23e97d594ddd0153020c506d5041048fbde1beb4 || >=73f7da5fd124f2cda9161e2e46114915e6e82e97 <737873a59905a54ca0d2d127ef882f3f88bf4379 || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <47d99828591d0fe8be4b9c8992ff3b8e47968db9 || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <b47bb899e04b5407c5a63fe88d4b6676586a6e84 || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <439d3e404f9d5e515911cc8132cde198b337c19e || >=3f14b377d01d8357eba032b4cabc8c1149b458b6 <8a7ed561671aa6a911a2de99e59ef670a4d0b1df || f5346df0591d10bc948761ca854b1fae6d2ef441 || >=5.15.148 <5.15.217 || >=6.1.75 <6.1.184 || >=6.6.14 <6.6.152 || >=6.7.2 <6.8 | b5dbecc2016e1692fd1c2532af9c41ba729cb747, 23e97d594ddd0153020c506d5041048fbde1beb4, 737873a59905a54ca0d2d127ef882f3f88bf4379, 47d99828591d0fe8be4b9c8992ff3b8e47968db9, b47bb899e04b5407c5a63fe88d4b6676586a6e84, 439d3e404f9d5e515911cc8132cde198b337c19e, 8a7ed561671aa6a911a2de99e59ef670a4d0b1df, 5.15.217, 6.1.184, 6.6.152, 6.8 |
Published upstream
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 22, 2026
In 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.
Quoted source text, attributed separately from HOL analysis.