{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-72347", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.920Z", "datePublished": "2026-08-15T05:55:51.665Z", "dateUpdated": "2026-08-17T05:43:05.530Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:43:05.530Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_connmark: reject invalid shift parameters\n\nRevision 2 of the CONNMARK target accepts user-controlled shift\nparameters and applies them to 32-bit mark values in\nconnmark_tg_shift().\n\nA shift_bits value of 32 or more triggers an undefined-shift bug when\nthe rule is evaluated. Invalid shift_dir values are also accepted and\nsilently fall back to the left-shift path.\n\nReject invalid revision-2 shift parameters in connmark_tg_check() so\nmalformed rules fail at installation time, before they can reach the\npacket path."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H", "baseScore": 7.3, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - Malformed CONNMARK rev2 rules are installed via IPT_SO_SET_REPLACE setsockopt or nftables NFNetlink (nft_compat); per kernel CNA guidance netfilter/xtables rule setup is Local even though installed rules later evaluate on ingress/egress packets through ipt_do_table/ip6t_do_table.\nAC:L - The attacker fully controls shift_bits and shift_dir in xt_connmark_tginfo2 when installing the rev2 CONNMARK target and can send conntrack-tracked packets to reliably hit connmark_tg_shift(); no race, memory layout, or victim state outside attacker control is required.\nPR:L - Installing CONNMARK iptables/nftables rules requires CAP_NET_ADMIN in the target network namespace, obtainable by unprivileged users via unshare -Urn; ip_tables.c do_ipt_set_ctl() and nfnetlink.c nfnetlink_rcv() enforce ns_capable/netlink_net_capable against the namespace user_ns.\nUI:N - The attacker installs the malformed CONNMARK rev2 rule and generates matching conntrack-associated traffic in their namespace; no separate victim action such as opening files, mounting media, or clicking links is required.\nS:U - Undefined shift during xt_CONNMARK packet targeting and resulting mark corruption remain within the host kernel security authority; this is standard local kernel netfilter compromise, not a VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:L - Undefined-behavior shifts on 32-bit mark values produce attacker-influenced unpredictable ct->mark and skb->mark results observable through conntrack netlink and mark-based iptables/nftables matches, leaking altered connection-classification state within the namespace.\nI:H - Invalid shift_bits or shift_dir corrupt connmark_tg_shift() output written to nf_conn->mark and skb->mark, subverting mark-dependent firewall, policy-routing, QoS, and multi-tenant container egress controls on cloud routers and internet-facing servers.\nA:H - Evaluating a malformed CONNMARK rev2 rule with shift_bits>=32 triggers C11 undefined-shift UB in connmark_tg_shift() during softirq netfilter processing; UBSAN-instrumented kernels panic on shift-out-of-bounds, and UB in the packet hot path can destabilize conntrack-driven forwarding."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/netfilter/xt_connmark.c"], "versions": [{"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "d8ce63d928b457fba7ed1e302492dfd32293671c", "status": "affected", "versionType": "git"}, {"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "9657bb11a6376ab0a79f05d433713d6944111e9d", "status": "affected", "versionType": "git"}, {"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "8ace320ac4416f5e5fbcd065309fb2dfcce787b0", "status": "affected", "versionType": "git"}, {"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "c3fa852d117b3fda72265e4230e3967db4a74fcf", "status": "affected", "versionType": "git"}, {"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "4eef84b09a3836919360c4232b0f16651a155eec", "status": "affected", "versionType": "git"}, {"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "230173cc6105bdfb2696d37e6e56687b003fbe63", "status": "affected", "versionType": "git"}, {"version": "472a73e00757b971d613d796374d2727b2e4954d", "lessThan": "1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc", "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/netfilter/xt_connmark.c"], "versions": [{"version": "4.17", "status": "affected"}, {"version": "0", "lessThan": "4.17", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "4.17", "versionEndExcluding": "5.15.212"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.1.178"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.6.145"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.12.97"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.18.40"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "7.1.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/d8ce63d928b457fba7ed1e302492dfd32293671c"}, {"url": "https://git.kernel.org/stable/c/9657bb11a6376ab0a79f05d433713d6944111e9d"}, {"url": "https://git.kernel.org/stable/c/8ace320ac4416f5e5fbcd065309fb2dfcce787b0"}, {"url": "https://git.kernel.org/stable/c/c3fa852d117b3fda72265e4230e3967db4a74fcf"}, {"url": "https://git.kernel.org/stable/c/4eef84b09a3836919360c4232b0f16651a155eec"}, {"url": "https://git.kernel.org/stable/c/230173cc6105bdfb2696d37e6e56687b003fbe63"}, {"url": "https://git.kernel.org/stable/c/1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc"}], "title": "netfilter: xt_connmark: reject invalid shift parameters", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/netfilter/xt_connmark.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "d8ce63d928b457fba7ed1e302492dfd32293671c", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}, {"lessThan": "9657bb11a6376ab0a79f05d433713d6944111e9d", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}, {"lessThan": "8ace320ac4416f5e5fbcd065309fb2dfcce787b0", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}, {"lessThan": "c3fa852d117b3fda72265e4230e3967db4a74fcf", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}, {"lessThan": "4eef84b09a3836919360c4232b0f16651a155eec", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}, {"lessThan": "230173cc6105bdfb2696d37e6e56687b003fbe63", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}, {"lessThan": "1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc", "status": "affected", "version": "472a73e00757b971d613d796374d2727b2e4954d", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/netfilter/xt_connmark.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.17"}, {"lessThan": "4.17", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.212", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.178", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.145", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.97", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.40", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "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: xt_connmark: reject invalid shift parameters\n\nRevision 2 of the CONNMARK target accepts user-controlled shift\nparameters and applies them to 32-bit mark values in\nconnmark_tg_shift().\n\nA shift_bits value of 32 or more triggers an undefined-shift bug when\nthe rule is evaluated. Invalid shift_dir values are also accepted and\nsilently fall back to the left-shift path.\n\nReject invalid revision-2 shift parameters in connmark_tg_check() so\nmalformed rules fail at installation time, before they can reach the\npacket path."}], "id": "CVE-2026-72347", "lastModified": "2026-08-17T06:18:38.643", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.3, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.5, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-15T06:22:08.070", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/230173cc6105bdfb2696d37e6e56687b003fbe63"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4eef84b09a3836919360c4232b0f16651a155eec"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8ace320ac4416f5e5fbcd065309fb2dfcce787b0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/9657bb11a6376ab0a79f05d433713d6944111e9d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c3fa852d117b3fda72265e4230e3967db4a74fcf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d8ce63d928b457fba7ed1e302492dfd32293671c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: netfilter: xt_connmark: reject invalid shift parameters", "id": "2516507", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2516507"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-1335", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnetfilter: xt_connmark: reject invalid shift parameters\nRevision 2 of the CONNMARK target accepts user-controlled shift\nparameters and applies them to 32-bit mark values in\nconnmark_tg_shift().\nA shift_bits value of 32 or more triggers an undefined-shift bug when\nthe rule is evaluated. Invalid shift_dir values are also accepted and\nsilently fall back to the left-shift path.\nReject invalid revision-2 shift parameters in connmark_tg_check() so\nmalformed rules fail at installation time, before they can reach the\npacket path.", "A flaw was found in the Linux kernel's `netfilter xt_connmark` module. This vulnerability occurs because the `CONNMARK` target, specifically revision 2, accepts user-controlled shift parameters without proper validation. An attacker with the ability to create netfilter rules could provide a `shift_bits` value of 32 or more, triggering an undefined-shift bug. This could lead to undefined behavior, potentially causing system instability or a denial of service."], "name": "CVE-2026-72347", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "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": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-72347\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-72347\nhttps://lore.kernel.org/linux-cve-announce/2026081511-CVE-2026-72347-6871@gregkh/T"], "threat_severity": "Low"}