{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74747", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.931Z", "datePublished": "2026-08-26T14:36:56.563Z", "dateUpdated": "2026-10-16T19:26:23.920Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-15T10:09:30.104Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: revalidate ihl to prevent out-of-bounds access\n\nWhile the outer IP header is already pulled into the skb head,\nwe must be careful and revalidate the embedded headers after\nreading them from the skb frags to prevent out-of-bounds\naccess.\n\nOne such place reported by Sashiko is ip_vs_nat_icmp() where\nlocal process can change the ihl field and after\nskb_ensure_writable() we can see larger value which is a\nproblem for the ip_send_check(cih) calls.\n\nAdd check to drop the packet if the ihl field is changed." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires a local process to TOCTOU-modify the embedded IPv4 ihl in skb frags between ip_vs_fill_iph_skb_icmp() and skb_ensure_writable(); remote ICMP to IPVS NAT hooks reaches ip_vs_nat_icmp() but cannot change skb backing memory without local access to the packet buffer.\nAC:L - A local attacker controls both sides of the race by concurrently injecting ICMP errors matching an IPVS NAT connection and mutating the embedded header ihl in userspace-backed skb frags during softirq processing; no uncontrollable victim state or heap layout is required.\nPR:L - Only a local account able to race skb frag modification (e.g., via raw/packet sockets with CAP_NET_RAW obtainable in user namespaces) against IPVS ICMP NAT handling on a host where IPVS is already configured is needed; init-namespace root is not required.\nUI:N - No victim user interaction is required; exploitation is driven entirely by attacker-controlled local packet injection and concurrent frag modification while IPVS processes ICMP errors on NAT-mode connections through LOCAL_IN, LOCAL_OUT, or FORWARD hooks.\nS:U - The out-of-bounds access corrupts kernel skb memory on the IPVS load-balancer host within the same kernel security authority; it does not cross VM, container, or IOMMU boundaries into a separate security scope.\nC:H - After skb_ensure_writable(), ip_send_check(cih) re-reads an attacker-inflated cih->ihl and ip_fast_csum() reads far beyond the validated skb region, enabling out-of-bounds kernel memory disclosure on internet-facing IPVS NAT nodes and kube-proxy IPVS clusters.\nI:H - The inflated ihl causes out-of-bounds access during ICMP NAT mangling in ip_vs_nat_icmp(), corrupting skb data beyond skb_ensure_writable()'s bound; such kernel memory corruption is exploitable for control-flow hijacking and privilege escalation on load balancers.\nA:H - Out-of-bounds access in ip_send_check(cih) during ICMP NAT handling can trigger kernel oops or panic; a local attacker can repeatedly race the TOCTOU on IPVS NAT nodes, causing sustained denial of service on critical infrastructure." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/ip_vs.h", "net/netfilter/ipvs/ip_vs_core.c", "net/netfilter/ipvs/ip_vs_xmit.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "eb81c8e758f49e04391f77d9470a6232bb5f1c7a", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "5365f012451fce2453f13a568dcb72ea534c1e4d", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "d93660df4dd1d116f608ada4a29a80a5d6f0a6ed", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/ip_vs.h", "net/netfilter/ipvs/ip_vs_core.c", "net/netfilter/ipvs/ip_vs_xmit.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.57", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.10", "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": "2.6.12", "versionEndExcluding": "6.18.57" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.1.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/eb81c8e758f49e04391f77d9470a6232bb5f1c7a" }, { "url": "https://git.kernel.org/stable/c/5365f012451fce2453f13a568dcb72ea534c1e4d" }, { "url": "https://git.kernel.org/stable/c/d93660df4dd1d116f608ada4a29a80a5d6f0a6ed" } ], "title": "ipvs: revalidate ihl to prevent out-of-bounds access", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-74747", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:16:17.710947Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:23.920Z" } } ] } }