CVE-2026-98255

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-98255", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.331Z", "datePublished": "2026-10-06T08:45:21.397Z", "dateUpdated": "2026-10-19T09:16:26.522Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:16:26.522Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: exclude old ACKs from tcp fast path\n\nExclude old ACKs before SND.UNA from the tcp fast path\nas well as ACKs after SND.NXT.\n\nSuch ACKs will fall through to the slow path, where tcp_ack()\nperforms the appropriate validation and challenge ACK handling\naccording to RFC5961 and Commit 3d501dd326fb1c7 (\"tcp: do not\naccept ACK of bytes we never sent\").\n\nThis prevents old ACKs from being accepted\nor modifying connection state as part of the fast path before\nappropriate ACK validation is applied.\nIn particular, this prevents payload carried by a segment with\nan excessively old ACK from advancing RCV.NXT before the ACK\nis rejected."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv4/tcp_input.c"], "versions": [{"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "07cacab90290f795bad2e566790f4ba8e84cdf5f", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "6eb9b697f50b73b9684e466c1e97f4ca8e947a59", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "b86e1e5a4bbcbbccde8b7a3d3486604b581f6628", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "1c8448db5cf35a13d82b0c9004ffdb49358883e7", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "8309dc2cc360056aa9cd2acfbfc25930798c3b66", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "ff037920c688ae6ca1153fec01e90e6782712455", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed", "status": "affected", "versionType": "git"}, {"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "lessThan": "f81e6c3fb06327bc49cdd6e559845293ba06a704", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv4/tcp_input.c"], "versions": [{"version": "4.14", "status": "affected"}, {"version": "0", "lessThan": "4.14", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "5.10.271"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "5.15.222"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.1.189"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.6.158"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.12.112"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.18.54"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "7.2.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f"}, {"url": "https://git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59"}, {"url": "https://git.kernel.org/stable/c/b86e1e5a4bbcbbccde8b7a3d3486604b581f6628"}, {"url": "https://git.kernel.org/stable/c/1c8448db5cf35a13d82b0c9004ffdb49358883e7"}, {"url": "https://git.kernel.org/stable/c/8309dc2cc360056aa9cd2acfbfc25930798c3b66"}, {"url": "https://git.kernel.org/stable/c/ff037920c688ae6ca1153fec01e90e6782712455"}, {"url": "https://git.kernel.org/stable/c/8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed"}, {"url": "https://git.kernel.org/stable/c/f81e6c3fb06327bc49cdd6e559845293ba06a704"}], "title": "tcp: exclude old ACKs from tcp fast path", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv4/tcp_input.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "07cacab90290f795bad2e566790f4ba8e84cdf5f", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "6eb9b697f50b73b9684e466c1e97f4ca8e947a59", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "b86e1e5a4bbcbbccde8b7a3d3486604b581f6628", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "1c8448db5cf35a13d82b0c9004ffdb49358883e7", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "8309dc2cc360056aa9cd2acfbfc25930798c3b66", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "ff037920c688ae6ca1153fec01e90e6782712455", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}, {"lessThan": "f81e6c3fb06327bc49cdd6e559845293ba06a704", "status": "affected", "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv4/tcp_input.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.14"}, {"lessThan": "4.14", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.271", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.222", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.189", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.158", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.112", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.54", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: exclude old ACKs from tcp fast path\n\nExclude old ACKs before SND.UNA from the tcp fast path\nas well as ACKs after SND.NXT.\n\nSuch ACKs will fall through to the slow path, where tcp_ack()\nperforms the appropriate validation and challenge ACK handling\naccording to RFC5961 and Commit 3d501dd326fb1c7 (\"tcp: do not\naccept ACK of bytes we never sent\").\n\nThis prevents old ACKs from being accepted\nor modifying connection state as part of the fast path before\nappropriate ACK validation is applied.\nIn particular, this prevents payload carried by a segment with\nan excessively old ACK from advancing RCV.NXT before the ACK\nis rejected."}], "id": "CVE-2026-98255", "lastModified": "2026-10-19T10:18:26.500", "metrics": {}, "published": "2026-10-06T09:18:14.210", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1c8448db5cf35a13d82b0c9004ffdb49358883e7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8309dc2cc360056aa9cd2acfbfc25930798c3b66"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b86e1e5a4bbcbbccde8b7a3d3486604b581f6628"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f81e6c3fb06327bc49cdd6e559845293ba06a704"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/ff037920c688ae6ca1153fec01e90e6782712455"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: tcp: exclude old ACKs from tcp fast path", "id": "2546518", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2546518"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-358", "details": ["In the Linux kernel, the following vulnerability has been resolved:\ntcp: exclude old ACKs from tcp fast path\nExclude old ACKs before SND.UNA from the tcp fast path\nas well as ACKs after SND.NXT.\nSuch ACKs will fall through to the slow path, where tcp_ack()\nperforms the appropriate validation and challenge ACK handling\naccording to RFC5961 and Commit 3d501dd326fb1c7 (\"tcp: do not\naccept ACK of bytes we never sent\").\nThis prevents old ACKs from being accepted\nor modifying connection state as part of the fast path before\nappropriate ACK validation is applied.\nIn particular, this prevents payload carried by a segment with\nan excessively old ACK from advancing RCV.NXT before the ACK\nis rejected.", "A flaw was found in the Linux kernel. Its TCP (Transmission Control Protocol) fast-path processing logic fails to properly filter out-of-bounds acknowledgment (ACK) packets before validating them. A remote attacker could exploit this vulnerability by sending network packets with outdated ACK numbers, potentially altering connection states and causing connection disruption."], "name": "CVE-2026-98255", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-10-06T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-98255\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-98255\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98255.mbox"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,07cacab90290f795bad2e566790f4ba8e84cdf5f)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,6eb9b697f50b73b9684e466c1e97f4ca8e947a59)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,b86e1e5a4bbcbbccde8b7a3d3486604b581f6628)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,1c8448db5cf35a13d82b0c9004ffdb49358883e7)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,8309dc2cc360056aa9cd2acfbfc25930798c3b66)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,ff037920c688ae6ca1153fec01e90e6782712455)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[31770e34e43d6c8dee129bfee77e56c34e61f0e5,f81e6c3fb06327bc49cdd6e559845293ba06a704)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "4.14"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,4.14)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.10.271,5.11.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.15.222,5.16.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.189,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.158,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.112,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.54,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.8,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.3-rc4,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-10-06T12:45:17.644102+00:00", "updated": "2026-10-11T05:15:17.416520+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}