CVE-2026-99283

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-99283", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.405Z", "datePublished": "2026-11-07T20:14:11.433Z", "dateUpdated": "2026-11-10T18:15:30.084Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-11-10T18:15:30.084Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: conntrack: tcp: use UNACK timeout for non-closing RST packets\n\nCommit be0502a3f2e9 (\"netfilter: conntrack: tcp: only close if RST\nmatches exact sequence\") keeps an established conntrack entry in\nESTABLISHED when an in-window RST does not match the expected sequence\nnumber exactly, so the endpoint can validate the RST with a challenge\nACK.\n\nThe timeout selection nevertheless uses the CLOSE timeout for every RST\npacket. The bug is that timeout selection is based on the packet type,\nnot on the state transition result: even when RST validation keeps\nnew_state in ESTABLISHED, the timeout is still forced to\nTCP_CONNTRACK_CLOSE.\n\nLinux TCP independently rate limits challenge ACKs per socket. A second\nnon-exact RST can therefore arrive after the first challenge ACK has\nrestored the timeout but before the rate limit expires. The second RST\nlowers the timeout to 10 seconds again while the endpoint suppresses the\nsecond challenge ACK, allowing the conntrack entry to expire while both\nTCP endpoints remain established.\n\nUsing the ESTABLISHED timeout for such RSTs would avoid this short\nexpiration window, but it could also retain stale entries for the\nfive-day default because conntrack cannot reliably match the endpoint's\nexact TCP state.\n\nUse the UNACK timeout for RST packets that leave the conntrack entry in\nTCP_CONNTRACK_ESTABLISHED. Exact-match RSTs and accepted RST packet\ntrains still fall through to timeouts[new_state], which preserves the\nCLOSE timeout when conntrack accepts the RST as closing the flow.\n\nThis avoids the aggressive 10-second expiration window for non-exact\nRSTs while preserving the short timeout for RSTs that conntrack accepts\nas closing the flow."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/netfilter/nf_conntrack_proto_tcp.c"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4d39a039d0b7737f8475c2431f18572b3b186a3b", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "0c6d33329960b2d884a399196c8403643d8a9de6", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "bf80e6802273a900311b44e47c9b1a59c6d2473c", "status": "affected", "versionType": "git"}, {"version": "0", "lessThan": "6.12.117", "status": "affected", "versionType": "semver"}, {"version": "0", "lessThan": "6.18.61", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/netfilter/nf_conntrack_proto_tcp.c"], "versions": [{"version": "6.12.117", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.61", "lessThanOrEqual": "6.18.*", "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:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.12.117"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.18.61"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4d39a039d0b7737f8475c2431f18572b3b186a3b"}, {"url": "https://git.kernel.org/stable/c/0c6d33329960b2d884a399196c8403643d8a9de6"}, {"url": "https://git.kernel.org/stable/c/bf80e6802273a900311b44e47c9b1a59c6d2473c"}], "title": "netfilter: conntrack: tcp: use UNACK timeout for non-closing RST packets", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/netfilter/nf_conntrack_proto_tcp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "4d39a039d0b7737f8475c2431f18572b3b186a3b", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "0c6d33329960b2d884a399196c8403643d8a9de6", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "bf80e6802273a900311b44e47c9b1a59c6d2473c", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "6.12.117", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThan": "6.18.61", "status": "affected", "version": "0", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/netfilter/nf_conntrack_proto_tcp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.117", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.61", "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\nnetfilter: conntrack: tcp: use UNACK timeout for non-closing RST packets\n\nCommit be0502a3f2e9 (\"netfilter: conntrack: tcp: only close if RST\nmatches exact sequence\") keeps an established conntrack entry in\nESTABLISHED when an in-window RST does not match the expected sequence\nnumber exactly, so the endpoint can validate the RST with a challenge\nACK.\n\nThe timeout selection nevertheless uses the CLOSE timeout for every RST\npacket. The bug is that timeout selection is based on the packet type,\nnot on the state transition result: even when RST validation keeps\nnew_state in ESTABLISHED, the timeout is still forced to\nTCP_CONNTRACK_CLOSE.\n\nLinux TCP independently rate limits challenge ACKs per socket. A second\nnon-exact RST can therefore arrive after the first challenge ACK has\nrestored the timeout but before the rate limit expires. The second RST\nlowers the timeout to 10 seconds again while the endpoint suppresses the\nsecond challenge ACK, allowing the conntrack entry to expire while both\nTCP endpoints remain established.\n\nUsing the ESTABLISHED timeout for such RSTs would avoid this short\nexpiration window, but it could also retain stale entries for the\nfive-day default because conntrack cannot reliably match the endpoint's\nexact TCP state.\n\nUse the UNACK timeout for RST packets that leave the conntrack entry in\nTCP_CONNTRACK_ESTABLISHED. Exact-match RSTs and accepted RST packet\ntrains still fall through to timeouts[new_state], which preserves the\nCLOSE timeout when conntrack accepts the RST as closing the flow.\n\nThis avoids the aggressive 10-second expiration window for non-exact\nRSTs while preserving the short timeout for RSTs that conntrack accepts\nas closing the flow."}], "id": "CVE-2026-99283", "lastModified": "2026-11-10T19:22:31.700", "metrics": {}, "published": "2026-11-07T21:17:00.477", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0c6d33329960b2d884a399196c8403643d8a9de6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4d39a039d0b7737f8475c2431f18572b3b186a3b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/bf80e6802273a900311b44e47c9b1a59c6d2473c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: kernel: Denial of Service via premature connection tracking expiration on TCP RST packets", "id": "2568681", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2568681"}, "csaw": false, "cvss3": {"cvss3_base_score": "3.7", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L", "status": "draft"}, "cwe": "CWE-826", "details": ["A flaw was found in the Linux kernel's Netfilter connection tracking subsystem. A remote attacker can cause a Denial of Service (DoS) by sending non-exact TCP reset (RST) packets to prematurely expire active connection tracking entries. When an in-window reset packet does not match the exact expected sequence number, the tracking system incorrectly applies a short close timeout instead of maintaining the connection. Because rate limiting suppresses subsequent challenge acknowledgments, active firewall tracking entries expire prematurely and drop established connections."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}, "name": "CVE-2026-99283", "package_state": [{"cpe": "cpe:/a:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:rhel_els:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:rhel_els:7", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:rhel_els:7", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/a:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/a:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/a:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:5", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-10", "product_name": "Red Hat OpenShift Container Platform 5"}, {"cpe": "cpe:/a:redhat:openshift:5", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 5"}], "public_date": "2026-11-07T20:14:11Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-99283\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-99283\nhttps://git.kernel.org/stable/c/0c6d33329960b2d884a399196c8403643d8a9de6\nhttps://git.kernel.org/stable/c/bf80e6802273a900311b44e47c9b1a59c6d2473c"], "statement": "This vulnerability is rated as Low severity because successful exploitation requires an attacker to guess or observe active TCP connection parameters\u2014including valid IP addresses, ports, and in-window sequence numbers\u2014and carefully time packet bursts to bypass TCP challenge ACK rate limits. The blast radius is confined to premature session eviction for targeted flows within Netfilter state tables, leading to dropped traffic for only the affected connection rather than host instability or kernel crashes. Broader system operations and unaffected network communications continue without disruption, as new connections can be established normally.", "threat_severity": "Low"}

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