Answer in brief
CVE-2026-80725 records a Critical severity (CVSS 9.8) vulnerability in net: gro: properly validate BIG TCP aggregation criteria. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=0fe79f28bfaf73b66b7b1562d2468f94aa03bd12 <37a5dcd6837fc2afc44a7bc3ed8af4e983783d46 || >=0fe79f28bfaf73b66b7b1562d2468f94aa03bd12 <e907bf694ed55bdfe421be99dba35751a655df25 || >=0fe79f28bfaf73b66b7b1562d2468f94aa03bd12 <03cb8cc2961f5f781d12e903782cb3815ed84b1c || >=0fe79f28bfaf73b66b7b1562d2468f94aa03bd12 <3ce832e2bd431d0c12ba525ed73ad8fbc4191da5 || >=0fe79f28bfaf73b66b7b1562d2468f94aa03bd12 <81be30c1f5f2bffda1f04c0efd0746af10b9643a | 37a5dcd6837fc2afc44a7bc3ed8af4e983783d46, e907bf694ed55bdfe421be99dba35751a655df25, 03cb8cc2961f5f781d12e903782cb3815ed84b1c, 3ce832e2bd431d0c12ba525ed73ad8fbc4191da5, 81be30c1f5f2bffda1f04c0efd0746af10b9643a |
| Linux/Linuxgeneric | 5.19 | Not reported |
Published upstream
Aug 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 29, 2026
In the Linux kernel, the following vulnerability has been resolved: net: gro: properly validate BIG TCP aggregation criteria When GRO attempts to aggregate packets beyond GRO_LEGACY_MAX_SIZE (64KB), BIG TCP should only be permitted for plain IPv4 TCP and plain IPv6 TCP (with sufficient MAC header room to insert the temporary HBH jumbo header). However, commit b1a78b9b9886 ("net: add support for ipv4 big tcp") loosened the check in skb_gro_receive(), leading to several issues: 1. skb_gro_receive() checked skb_headroom(p) instead of the actual space before the MAC header (p->mac_header). Because skb_headroom(p) includes mac_len, crafted frames (e.g. injected via AF_PACKET) can pass the check with p->mac_header < 8 bytes. When ipv6_gro_complete() inserts the temporary HBH jumbo header, the memmove() starts before skb->head, causing an out-of-bounds write and wrapping skb->mac_header. 2. It allowed non-IP protocols such as software VLAN (ETH_P_8021Q / ETH_P_8021AD) to aggregate beyond 64KB because p->protocol != ETH_P_IPV6 was true. 3. It checked p->encapsulation instead of NAPI_GRO_CB(skb)->encap_mark, allowing encapsulated flows (e.g. SIT / IPv6-in-IPv4) to aggregate beyond 64KB. Fix skb_gro_receive() to strictly enforce: - NAPI_GRO_CB(skb)->proto == IPPROTO_TCP - Not encapsulated (!NAPI_GRO_CB(skb)->encap_mark && !p->encapsulation) - Protocol must be either ETH_P_IP or ETH_P_IPV6 - If ETH_P_IPV6, p->mac_header must be at least sizeof(struct hop_jumbo_hdr) Returning -E2BIG from skb_gro_receive() ensures that packets which cannot become BIG TCP are cleanly flushed at <= 64KB and delivered intact without dropping. This issue does not exist in mainline (7.0+) because the subsystem was rewritten in commit 81be30c1f5f2 ("net/ipv6: Drop HBH for BIG TCP on RX side"), making this fix relevant only for older stable branches like 6.18.y.
Quoted source text, attributed separately from HOL analysis.