{"api_version":"1","generated_at":"2026-06-03T11:06:36+00:00","cve":"CVE-2026-45859","urls":{"html":"https://cve.report/CVE-2026-45859","api":"https://cve.report/api/cve/CVE-2026-45859.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-45859","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-45859"},"summary":{"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-05-27 14:16:58","updated_at":"2026-05-30 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45859","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb 79b713ef4261a8ead96af4703f89d0b5f25532e2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb 23901aa6b8a2f294c4b774436b4691f3ff863a8f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb b740e7ddd7ca0dbfeafca3f5e52717206cf28524 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb 207b3ebacb6113acaaec0d171d5307032c690004 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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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."}],"metrics":[{"cvssV3_1":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-05-30T10:45:35.721Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"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"}],"title":"netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-45859","datePublished":"2026-05-27T12:15:39.322Z","dateReserved":"2026-05-13T15:03:33.079Z","dateUpdated":"2026-05-30T10:45:35.721Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-27 14:16:58","lastModifiedDate":"2026-05-30 11:17:14","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"45859","Ordinal":"1","Title":"netfilter: nfnetlink_queue: do shared-unconfirmed check before s","CVE":"CVE-2026-45859","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"45859","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"netfilter: nfnetlink_queue: do shared-unconfirmed check before s"}]}}}