{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80725", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.789Z", "datePublished": "2026-08-29T06:39:35.212Z", "dateUpdated": "2026-10-16T19:26:35.734Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-04T04:58:15.396Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: gro: properly validate BIG TCP aggregation criteria\n\nWhen GRO attempts to aggregate packets beyond GRO_LEGACY_MAX_SIZE (64KB),\nBIG TCP should only be permitted for plain IPv4 TCP and plain IPv6 TCP\n(with sufficient MAC header room to insert the temporary HBH jumbo header).\n\nHowever, commit b1a78b9b9886 (\"net: add support for ipv4 big tcp\")\nloosened the check in skb_gro_receive(), leading to several issues:\n\n1. skb_gro_receive() checked skb_headroom(p) instead of the actual space\n before the MAC header (p->mac_header). Because skb_headroom(p) includes\n mac_len, crafted frames (e.g. injected via AF_PACKET) can pass the check\n with p->mac_header < 8 bytes. When ipv6_gro_complete() inserts the\n temporary HBH jumbo header, the memmove() starts before skb->head,\n causing an out-of-bounds write and wrapping skb->mac_header.\n2. It allowed non-IP protocols such as software VLAN (ETH_P_8021Q /\n ETH_P_8021AD) to aggregate beyond 64KB because\n p->protocol != ETH_P_IPV6 was true.\n3. It checked p->encapsulation instead of NAPI_GRO_CB(skb)->encap_mark,\n allowing encapsulated flows (e.g. SIT / IPv6-in-IPv4) to aggregate\n beyond 64KB.\n\nFix skb_gro_receive() to strictly enforce:\n- NAPI_GRO_CB(skb)->proto == IPPROTO_TCP\n- Not encapsulated (!NAPI_GRO_CB(skb)->encap_mark && !p->encapsulation)\n- Protocol must be either ETH_P_IP or ETH_P_IPV6\n- If ETH_P_IPV6, p->mac_header must be at least\n sizeof(struct hop_jumbo_hdr)\n\nReturning -E2BIG from skb_gro_receive() ensures that packets which cannot\nbecome BIG TCP are cleanly flushed at <= 64KB and delivered intact without\ndropping.\n\nThis issue does not exist in mainline (7.0+) because the subsystem was\nrewritten in commit 81be30c1f5f2 (\"net/ipv6: Drop HBH for BIG TCP on RX\nside\"), making this fix relevant only for older stable branches like\n6.18.y." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The flaw is in skb_gro_receive() on the netdev NAPI GRO ingress path (netif_receive_skb→napi_gro_receive→dev_gro_receive→tcp/ipv6 gro handlers); remote peers can deliver crafted in-flow TCP streams to internet-facing interfaces without local access.\nAC:L - On Big TCP deployments with gro_max_size>64KB, an attacker reliably coalesces past GRO_LEGACY_MAX_SIZE by sending many same-flow TCP segments; AF_PACKET injection also gives deterministic header layout control without races or victim-dependent heap layout.\nPR:N - RX GRO runs in softirq on all received packets before socket authentication; no target credentials or capabilities are required. Elevated gro_max_size is an admin tuning prerequisite of the Big TCP server class, not an attacker privilege.\nUI:N - Packet reception and GRO aggregation are automatic kernel network-stack processing triggered solely by attacker-sent traffic; no victim mount, file open, or other interaction is required.\nS:U - Impact is kernel skb/heap memory corruption within the host kernel security authority; exploitation does not cross VM, container, or IOMMU boundaries that would warrant scope-changed scoring.\nC:H - When undersized mac_header room passes the broken skb_headroom check, ipv6_gro_complete() memmove() for the temporary HBH jumbo header writes before skb->head, corrupting adjacent kernel memory and enabling information disclosure from attacker-influenced out-of-bounds writes.\nI:H - The same invalid BIG TCP aggregation drives attacker-controlled memmove/header corruption that wraps skb->mac_header, yielding an out-of-bounds write primitive suitable for heap object corruption, control-flow hijacking, and local privilege escalation.\nA:H - The defective memmove or invalid >64KB aggregation on disallowed VLAN, encapsulated, or malformed flows can oops or panic the kernel during GRO completion, and a remote attacker can trigger this repeatedly to deny service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/gro.c" ], "versions": [ { "version": "0fe79f28bfaf73b66b7b1562d2468f94aa03bd12", "lessThan": "37a5dcd6837fc2afc44a7bc3ed8af4e983783d46", "status": "affected", "versionType": "git" }, { "version": "0fe79f28bfaf73b66b7b1562d2468f94aa03bd12", "lessThan": "e907bf694ed55bdfe421be99dba35751a655df25", "status": "affected", "versionType": "git" }, { "version": "0fe79f28bfaf73b66b7b1562d2468f94aa03bd12", "lessThan": "03cb8cc2961f5f781d12e903782cb3815ed84b1c", "status": "affected", "versionType": "git" }, { "version": "0fe79f28bfaf73b66b7b1562d2468f94aa03bd12", "lessThan": "3ce832e2bd431d0c12ba525ed73ad8fbc4191da5", "status": "affected", "versionType": "git" }, { "version": "0fe79f28bfaf73b66b7b1562d2468f94aa03bd12", "lessThan": "81be30c1f5f2bffda1f04c0efd0746af10b9643a", "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/core/gro.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.185", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.154", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.106", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.47", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "5.19", "versionEndExcluding": "6.1.185" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.154" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.106" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.18.47" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/37a5dcd6837fc2afc44a7bc3ed8af4e983783d46" }, { "url": "https://git.kernel.org/stable/c/e907bf694ed55bdfe421be99dba35751a655df25" }, { "url": "https://git.kernel.org/stable/c/03cb8cc2961f5f781d12e903782cb3815ed84b1c" }, { "url": "https://git.kernel.org/stable/c/3ce832e2bd431d0c12ba525ed73ad8fbc4191da5" }, { "url": "https://git.kernel.org/stable/c/81be30c1f5f2bffda1f04c0efd0746af10b9643a" } ], "title": "net: gro: properly validate BIG TCP aggregation criteria", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-80725", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:21:06.422941Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:35.734Z" } } ] } }