{"id":"CVE-2026-45859","state":"PUBLISHED","title":"netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation\n\nUlrich reports a regression with nfqueue:\n\nIf an application did not set the 'F_GSO' capability flag and a gso\npacket with an unconfirmed nf_conn entry is received all packets are\nnow dropped instead of queued, because the check happens after\nskb_gso_segment().  In that case, we did have exclusive ownership\nof the skb and its associated conntrack entry.  The elevated use\ncount is due to skb_clone happening via skb_gso_segment().\n\nMove the check so that its peformed vs. the aggregated packet.\n\nThen, annotate the individual segments except the first one so we\ncan do a 2nd check at reinject time.\n\nFor the normal case, where userspace does in-order reinjects, this avoids\npacket drops: first reinjected segment continues traversal and confirms\nentry, remaining segments observe the confirmed entry.\n\nWhile at it, simplify nf_ct_drop_unconfirmed(): We only care about\nunconfirmed entries with a refcnt > 1, there is no need to special-case\ndying entries.\n\nThis only happens with UDP.  With TCP, the only unconfirmed packet will\nbe the TCP SYN, those aren't aggregated by GRO.\n\nNext patch adds a udpgro test case to cover this scenario.","publishedAt":"2026-05-27T12:15:39.322Z","updatedAt":"2026-10-30T12:25:38.053Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6dcc8ba8a6074bb79040f502dc66ad23a58a1c86","status":"affected","lessThan":"4666688657e1054278b836b825fb88b2907e2da2","versionType":"git"},{"version":"74e6eb7fd27ef1ccc68041dbc66e6d80d2e4a1a0","status":"affected","lessThan":"aead84bdacd77e08357fd718e5dcaffaf387f3c3","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"79b713ef4261a8ead96af4703f89d0b5f25532e2","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"23901aa6b8a2f294c4b774436b4691f3ff863a8f","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"b740e7ddd7ca0dbfeafca3f5e52717206cf28524","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"207b3ebacb6113acaaec0d171d5307032c690004","versionType":"git"},{"version":"6c4a0ba674f410ab99a30a16f32dac0ebfed5cd3","status":"affected","versionType":"git"},{"version":"025b3326c5c409b372d0103ad30f174e55adbd1b","status":"affected","versionType":"git"},{"version":"6.1.107","status":"affected","lessThan":"6.1.191","versionType":"semver"},{"version":"6.6.48","status":"affected","lessThan":"6.6.160","versionType":"semver"},{"version":"5.15.166","status":"affected","lessThan":"5.16","versionType":"semver"},{"version":"6.10.7","status":"affected","lessThan":"6.11","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/netfilter/nf_queue.h","net/netfilter/nfnetlink_queue.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.14","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.4","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/netfilter/nf_queue.h","net/netfilter/nfnetlink_queue.c"]}],"references":["https://git.kernel.org/stable/c/4666688657e1054278b836b825fb88b2907e2da2","https://git.kernel.org/stable/c/aead84bdacd77e08357fd718e5dcaffaf387f3c3","https://git.kernel.org/stable/c/79b713ef4261a8ead96af4703f89d0b5f25532e2","https://git.kernel.org/stable/c/23901aa6b8a2f294c4b774436b4691f3ff863a8f","https://git.kernel.org/stable/c/b740e7ddd7ca0dbfeafca3f5e52717206cf28524","https://git.kernel.org/stable/c/207b3ebacb6113acaaec0d171d5307032c690004"],"weaknesses":["CWE-400"],"ingestedAt":"2026-10-30T12:42:04.495Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/45xxx/CVE-2026-45859.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-45859","state":"PUBLISHED","datePublished":"2026-05-27T12:15:39.322Z","dateUpdated":"2026-10-30T12:25:38.053Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.079Z"},"containers":{"cna":{"title":"netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation\n\nUlrich reports a regression with nfqueue:\n\nIf an application did not set the 'F_GSO' capability flag and a gso\npacket with an unconfirmed nf_conn entry is received all packets are\nnow dropped instead of queued, because the check happens after\nskb_gso_segment().  In that case, we did have exclusive ownership\nof the skb and its associated conntrack entry.  The elevated use\ncount is due to skb_clone happening via skb_gso_segment().\n\nMove the check so that its peformed vs. the aggregated packet.\n\nThen, annotate the individual segments except the first one so we\ncan do a 2nd check at reinject time.\n\nFor the normal case, where userspace does in-order reinjects, this avoids\npacket drops: first reinjected segment continues traversal and confirms\nentry, remaining segments observe the confirmed entry.\n\nWhile at it, simplify nf_ct_drop_unconfirmed(): We only care about\nunconfirmed entries with a refcnt > 1, there is no need to special-case\ndying entries.\n\nThis only happens with UDP.  With TCP, the only unconfirmed packet will\nbe the TCP SYN, those aren't aggregated by GRO.\n\nNext patch adds a udpgro test case to cover this scenario."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6dcc8ba8a6074bb79040f502dc66ad23a58a1c86","status":"affected","lessThan":"4666688657e1054278b836b825fb88b2907e2da2","versionType":"git"},{"version":"74e6eb7fd27ef1ccc68041dbc66e6d80d2e4a1a0","status":"affected","lessThan":"aead84bdacd77e08357fd718e5dcaffaf387f3c3","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"79b713ef4261a8ead96af4703f89d0b5f25532e2","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"23901aa6b8a2f294c4b774436b4691f3ff863a8f","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"b740e7ddd7ca0dbfeafca3f5e52717206cf28524","versionType":"git"},{"version":"7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb","status":"affected","lessThan":"207b3ebacb6113acaaec0d171d5307032c690004","versionType":"git"},{"version":"6c4a0ba674f410ab99a30a16f32dac0ebfed5cd3","status":"affected","versionType":"git"},{"version":"025b3326c5c409b372d0103ad30f174e55adbd1b","status":"affected","versionType":"git"},{"version":"6.1.107","status":"affected","lessThan":"6.1.191","versionType":"semver"},{"version":"6.6.48","status":"affected","lessThan":"6.6.160","versionType":"semver"},{"version":"5.15.166","status":"affected","lessThan":"5.16","versionType":"semver"},{"version":"6.10.7","status":"affected","lessThan":"6.11","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/netfilter/nf_queue.h","net/netfilter/nfnetlink_queue.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.14","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.4","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/netfilter/nf_queue.h","net/netfilter/nfnetlink_queue.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4666688657e1054278b836b825fb88b2907e2da2"},{"url":"https://git.kernel.org/stable/c/aead84bdacd77e08357fd718e5dcaffaf387f3c3"},{"url":"https://git.kernel.org/stable/c/79b713ef4261a8ead96af4703f89d0b5f25532e2"},{"url":"https://git.kernel.org/stable/c/23901aa6b8a2f294c4b774436b4691f3ff863a8f"},{"url":"https://git.kernel.org/stable/c/b740e7ddd7ca0dbfeafca3f5e52717206cf28524"},{"url":"https://git.kernel.org/stable/c/207b3ebacb6113acaaec0d171d5307032c690004"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable nfnetlink_queue path processes packets that hit an NFQUEUE netfilter verdict; GRO-aggregated UDP traffic received from the network reaches it, so the dropping condition is triggered by remote network packets.\nAC:L - Once an nfqueue without F_GSO exists, an attacker reliably triggers the drop by sending a UDP burst that GRO coalesces into a GSO skb for a new (unconfirmed) flow; no uncontrollable condition is required.\nPR:N - Triggering the condition requires only sending network traffic to the host; no authentication or privileges are needed by the remote sender.\nUI:N - The packet drop occurs automatically during kernel packet processing with no victim interaction.\nS:U - The impact is confined to the kernel's own network packet processing; no security boundary is crossed.\nC:N - The bug only causes packets to be dropped; no kernel memory is read or disclosed.\nI:N - No data is modified or written; dropped packets are simply not delivered, which is an availability rather than integrity effect.\nA:H - All GSO-aggregated UDP packets of new (unconfirmed) conntrack flows are dropped on a non-F_GSO nfqueue, denying establishment/processing of those new flows — a sustained, network-triggerable denial of that traffic class."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:25:38.053Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.107","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.48","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.75"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.19.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.0"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.166"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10.7"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-45859","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:18:05.838159Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","type":"CWE","description":"CWE-400 Uncontrolled Resource Consumption"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:26:38.615Z"}}]}}}