{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63992", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.025Z", "datePublished": "2026-07-19T14:56:12.528Z", "dateUpdated": "2026-08-05T12:37:55.661Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:55.661Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: do not assume transport header in iptunnel_pmtud_check_icmp()\n\nIn some cases, iptunnel_pmtud_check_icmp() can be called while\nskb transport header is not set.\n\nThis triggers an out-of-bound access, because\n(typeof(skb->transport_header))~0U is 65535.\n\nAccess the icmp header based on IPv4 network header,\nafter making sure icmp->type is present in skb linear part.\n\nNote that iptunnel_pmtud_check_icmpv6()) is fine." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 9.1, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable code runs on the VXLAN/GENEVE transmit path when processing remotely received UDP-encapsulated tunnel traffic (or L2 frames forwarded through a bridge port), which is reachable by sending crafted packets over the network to the victim VTEP.\nAC:L - The attacker fully controls the inner IPv4 header fields (DF bit, length, addresses) and can reliably craft oversized packets that exceed the tunnel-adjusted PMTU on bridge-port tunnel devices without depending on race timing or uncontrollable system state.\nPR:N - Exploitation requires only the ability to send network packets to a host with VXLAN/GENEVE bridged; no local account, authentication, or capabilities on the victim are needed.\nUI:N - No victim user action is required; the kernel processes attacker-supplied packets automatically through the tunnel receive, bridge forward, and re-encapsulation path.\nS:U - The out-of-bounds read and resulting kernel oops occur within the kernel network stack on the same host; there is no crossing of a VM, container, or IOMMU security boundary beyond standard kernel memory safety failure.\nC:H - Reading through `icmp_hdr(skb)` when `transport_header` is unset causes an out-of-bounds read at `skb->head + 65535`, potentially disclosing adjacent kernel memory beyond the skb buffer before any bounds checking occurs.\nI:N - The flaw is an out-of-bounds read of the ICMP type field; it does not directly modify or write kernel memory, though it may cause a kernel fault.\nA:H - The invalid pointer dereference at offset 65535 can trigger a kernel oops or panic when accessing unmapped memory, causing denial of service on the affected host." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/ip_tunnel_core.c" ], "versions": [ { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "5a92cb45e34749865d03daf8d3500f77b5f6644c", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "c7b7ec3e69e673c0d6b57f74d21da50c485c598e", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "7f4f7efe7f30edd29c4988de01728bf2398217e4", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "a096b6e34f602950af9a2b0856cd93a5f4c276d7", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "43368636c663cff6e59dde93cf4b8e43ac28eb93", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "cb549df9ce4ee15c9d5b19ddab12cf2128e4313c", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "509323077ef79a26ba0c60bb556e45c12c398b2d", "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/ip_tunnel_core.c" ], "versions": [ { "version": "5.9", "status": "affected" }, { "version": "0", "lessThan": "5.9", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "5.9", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c" }, { "url": "https://git.kernel.org/stable/c/c7b7ec3e69e673c0d6b57f74d21da50c485c598e" }, { "url": "https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4" }, { "url": "https://git.kernel.org/stable/c/e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec" }, { "url": "https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7" }, { "url": "https://git.kernel.org/stable/c/43368636c663cff6e59dde93cf4b8e43ac28eb93" }, { "url": "https://git.kernel.org/stable/c/cb549df9ce4ee15c9d5b19ddab12cf2128e4313c" }, { "url": "https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d" } ], "title": "tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()", "x_generator": { "engine": "bippy-1.2.0" } } } }