{"api_version":"1","generated_at":"2026-10-21T15:35:19+00:00","cve":"CVE-2026-98549","urls":{"html":"https://cve.report/CVE-2026-98549","api":"https://cve.report/api/cve/CVE-2026-98549.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98549","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98549"},"summary":{"title":"tcp: prevent collapsing skbs across boundary in rtx queue","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: prevent collapsing skbs across boundary in rtx queue\n\ntcp_write_collapse_fence() sets TCP_SKB_CB(skb)->eor = 1 on\ntcp_write_queue_tail(sk) to prevent skbs queued after a switch to\ndevice encryption from being collapsed into earlier skbs.\n\nThe fence is a no-op if all earlier data has already been transmitted\nwhen the switch happens: sk->sk_write_queue is empty. The not yet\nacknowledged earlier skbs wait in sk->tcp_rtx_queue with eor 0.\n\nOn a subsequent retransmit or SACK shift, tcp_retrans_try_collapse() or\ntcp_shift_skb_data() can then merge an skb queued after the switch into\none queued before it.\n\nBoth users of the fence are affected:\n\n- psp: devices only encrypt skbs with skb->decrypted set. The merged skb\n  keeps decrypted = 0 from the earlier skb, so merged data sent after\n  psp_sock_assoc_set_tx() is retransmitted in cleartext.\n\n- tls device offload: the merged skb straddles the start marker set in\n  tls_set_device_offload(). The software fallback (fill_sg_in() returns\n  -EINVAL) and the mlx5, nfp and funeth drivers cannot handle such an\n  skb and drop it. Every retransmit rebuilds the same skb, so the\n  connection stalls.\n\nFix this in two places, for defense in depth:\n\n1. Fall back to tcp_rtx_queue_tail(sk) in tcp_write_collapse_fence()\n   when tcp_write_queue_tail(sk) is NULL.\n\n2. Check !skb_cmp_decrypted(to, from) in tcp_skb_can_collapse(), as\n   tcp_skb_can_collapse_rx() does on receive. skb_shift(), which both\n   collapse paths call, already has a DEBUG_NET_WARN_ON_ONCE() for this\n   condition.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-18 16:17:06","updated_at":"2026-10-21 13:21:32"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/1ae7aee395245874d797890380d9192bd858fb7e","name":"https://git.kernel.org/stable/c/1ae7aee395245874d797890380d9192bd858fb7e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9e2a2f98e8c0197108c6d97a1fa43bfd89071c30","name":"https://git.kernel.org/stable/c/9e2a2f98e8c0197108c6d97a1fa43bfd89071c30","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fc6d80eb504458d6416b75a94188b268c95c6533","name":"https://git.kernel.org/stable/c/fc6d80eb504458d6416b75a94188b268c95c6533","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/08e835f5ec6e261c79d8c39f8618b3af29e3b0da","name":"https://git.kernel.org/stable/c/08e835f5ec6e261c79d8c39f8618b3af29e3b0da","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7ba87509c54cd519e7ed362e0c85e8431f066a18","name":"https://git.kernel.org/stable/c/7ba87509c54cd519e7ed362e0c85e8431f066a18","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98549","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98549","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e8f69799810c32dd40c6724d829eccc70baad07f 9e2a2f98e8c0197108c6d97a1fa43bfd89071c30 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e8f69799810c32dd40c6724d829eccc70baad07f 1ae7aee395245874d797890380d9192bd858fb7e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e8f69799810c32dd40c6724d829eccc70baad07f 7ba87509c54cd519e7ed362e0c85e8431f066a18 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e8f69799810c32dd40c6724d829eccc70baad07f 08e835f5ec6e261c79d8c39f8618b3af29e3b0da git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e8f69799810c32dd40c6724d829eccc70baad07f fc6d80eb504458d6416b75a94188b268c95c6533 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.18","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.18 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.160 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.112 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.55 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.9 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/tcp.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"9e2a2f98e8c0197108c6d97a1fa43bfd89071c30","status":"affected","version":"e8f69799810c32dd40c6724d829eccc70baad07f","versionType":"git"},{"lessThan":"1ae7aee395245874d797890380d9192bd858fb7e","status":"affected","version":"e8f69799810c32dd40c6724d829eccc70baad07f","versionType":"git"},{"lessThan":"7ba87509c54cd519e7ed362e0c85e8431f066a18","status":"affected","version":"e8f69799810c32dd40c6724d829eccc70baad07f","versionType":"git"},{"lessThan":"08e835f5ec6e261c79d8c39f8618b3af29e3b0da","status":"affected","version":"e8f69799810c32dd40c6724d829eccc70baad07f","versionType":"git"},{"lessThan":"fc6d80eb504458d6416b75a94188b268c95c6533","status":"affected","version":"e8f69799810c32dd40c6724d829eccc70baad07f","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/tcp.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.18"},{"lessThan":"4.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.160","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.112","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.55","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.9","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.160","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.112","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.55","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.9","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"4.18","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: prevent collapsing skbs across boundary in rtx queue\n\ntcp_write_collapse_fence() sets TCP_SKB_CB(skb)->eor = 1 on\ntcp_write_queue_tail(sk) to prevent skbs queued after a switch to\ndevice encryption from being collapsed into earlier skbs.\n\nThe fence is a no-op if all earlier data has already been transmitted\nwhen the switch happens: sk->sk_write_queue is empty. The not yet\nacknowledged earlier skbs wait in sk->tcp_rtx_queue with eor 0.\n\nOn a subsequent retransmit or SACK shift, tcp_retrans_try_collapse() or\ntcp_shift_skb_data() can then merge an skb queued after the switch into\none queued before it.\n\nBoth users of the fence are affected:\n\n- psp: devices only encrypt skbs with skb->decrypted set. The merged skb\n  keeps decrypted = 0 from the earlier skb, so merged data sent after\n  psp_sock_assoc_set_tx() is retransmitted in cleartext.\n\n- tls device offload: the merged skb straddles the start marker set in\n  tls_set_device_offload(). The software fallback (fill_sg_in() returns\n  -EINVAL) and the mlx5, nfp and funeth drivers cannot handle such an\n  skb and drop it. Every retransmit rebuilds the same skb, so the\n  connection stalls.\n\nFix this in two places, for defense in depth:\n\n1. Fall back to tcp_rtx_queue_tail(sk) in tcp_write_collapse_fence()\n   when tcp_write_queue_tail(sk) is NULL.\n\n2. Check !skb_cmp_decrypted(to, from) in tcp_skb_can_collapse(), as\n   tcp_skb_can_collapse_rx() does on receive. skb_shift(), which both\n   collapse paths call, already has a DEBUG_NET_WARN_ON_ONCE() for this\n   condition."}],"providerMetadata":{"dateUpdated":"2026-10-21T12:55:21.584Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/9e2a2f98e8c0197108c6d97a1fa43bfd89071c30"},{"url":"https://git.kernel.org/stable/c/1ae7aee395245874d797890380d9192bd858fb7e"},{"url":"https://git.kernel.org/stable/c/7ba87509c54cd519e7ed362e0c85e8431f066a18"},{"url":"https://git.kernel.org/stable/c/08e835f5ec6e261c79d8c39f8618b3af29e3b0da"},{"url":"https://git.kernel.org/stable/c/fc6d80eb504458d6416b75a94188b268c95c6533"}],"title":"tcp: prevent collapsing skbs across boundary in rtx queue","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98549","datePublished":"2026-10-18T15:18:17.361Z","dateReserved":"2026-09-25T10:25:14.356Z","dateUpdated":"2026-10-21T12:55:21.584Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-18 16:17:06","lastModifiedDate":"2026-10-21 13:21:32","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98549","Ordinal":"1","Title":"tcp: prevent collapsing skbs across boundary in rtx queue","CVE":"CVE-2026-98549","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98549","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: prevent collapsing skbs across boundary in rtx queue\n\ntcp_write_collapse_fence() sets TCP_SKB_CB(skb)->eor = 1 on\ntcp_write_queue_tail(sk) to prevent skbs queued after a switch to\ndevice encryption from being collapsed into earlier skbs.\n\nThe fence is a no-op if all earlier data has already been transmitted\nwhen the switch happens: sk->sk_write_queue is empty. The not yet\nacknowledged earlier skbs wait in sk->tcp_rtx_queue with eor 0.\n\nOn a subsequent retransmit or SACK shift, tcp_retrans_try_collapse() or\ntcp_shift_skb_data() can then merge an skb queued after the switch into\none queued before it.\n\nBoth users of the fence are affected:\n\n- psp: devices only encrypt skbs with skb->decrypted set. The merged skb\n  keeps decrypted = 0 from the earlier skb, so merged data sent after\n  psp_sock_assoc_set_tx() is retransmitted in cleartext.\n\n- tls device offload: the merged skb straddles the start marker set in\n  tls_set_device_offload(). The software fallback (fill_sg_in() returns\n  -EINVAL) and the mlx5, nfp and funeth drivers cannot handle such an\n  skb and drop it. Every retransmit rebuilds the same skb, so the\n  connection stalls.\n\nFix this in two places, for defense in depth:\n\n1. Fall back to tcp_rtx_queue_tail(sk) in tcp_write_collapse_fence()\n   when tcp_write_queue_tail(sk) is NULL.\n\n2. Check !skb_cmp_decrypted(to, from) in tcp_skb_can_collapse(), as\n   tcp_skb_can_collapse_rx() does on receive. skb_shift(), which both\n   collapse paths call, already has a DEBUG_NET_WARN_ON_ONCE() for this\n   condition.","Type":"Description","Title":"tcp: prevent collapsing skbs across boundary in rtx queue"}]}}}