Answer in brief
CVE-2026-98955 records a Unknown severity vulnerability in flow_dissector: avoid u16 truncation of skb->len when computing thoff. 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.
A CVSS score is not reported in the current record. 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 | >=d0c081b49137cd3200f2023c0875723be66e7ce5 <d9e08836d06c84abb18470c94b12b131eaccdc7d || >=d0c081b49137cd3200f2023c0875723be66e7ce5 <50d0cd575cab763f833d6ac6eb6550b23a0b3dae || >=d0c081b49137cd3200f2023c0875723be66e7ce5 <9993e6a0ac1b5b3101ffba702cacb9f42b9909d8 || >=d0c081b49137cd3200f2023c0875723be66e7ce5 <52efce4755a4b8b82039caa773645ffc80b25362 || >=d0c081b49137cd3200f2023c0875723be66e7ce5 <99bda1ecbd56905f8bd934b9cdccd3bd251192b1 || d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc || eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1 || 80f327285cab6ab8e10c3ea03278add5dd99fb02 || >=4.4.114 <4.5 || >=4.9.79 <4.10 || >=4.14.16 <4.15 | d9e08836d06c84abb18470c94b12b131eaccdc7d, 50d0cd575cab763f833d6ac6eb6550b23a0b3dae, 9993e6a0ac1b5b3101ffba702cacb9f42b9909d8, 52efce4755a4b8b82039caa773645ffc80b25362, 99bda1ecbd56905f8bd934b9cdccd3bd251192b1, 4.5, 4.10, 4.15 |
| Linux/Linuxgeneric | 4.15 | Not reported |
Published upstream
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 23, 2026
In the Linux kernel, the following vulnerability has been resolved: flow_dissector: avoid u16 truncation of skb->len when computing thoff __skb_flow_dissect() computes key_control->thoff using: key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); min_t(u16, ...) casts both arguments to u16 before comparing them. Whenever skb->len (or hlen) modulo 65536 is smaller than nhoff, the truncated length wins and thoff is set to a bogus small value, even when the dissection succeeded. For example, an IPv4/TCP frame with skb->len == 65540 and nhoff == 34 gets thoff == 4, so callers such as skb_probe_transport_header() point the transport header inside the Ethernet header. Such skbs are not exotic: - At the time of commit d0c081b49137 ("flow_dissector: properly cap thoff field"), AF_PACKET with PACKET_VNET_HDR could already build GSO skbs larger than 64KB (MTU checks are skipped for GSO, and alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0 pages on top of the linear part). - BIG TCP now makes skbs larger than 64KB common. - The following patch makes tun_get_user() dissect IFF_TAP frames before eth_type_trans() pulls the Ethernet header, so a GSO frame carrying a 65522..65535 byte L3 packet will be dissected with skb->len in [65536, 65549]. Compare as u32 instead. If the resulting offset cannot be represented in the u16 key_control->thoff, cap it to U16_MAX and report the dissection as failed rather than silently returning a wrong transport offset. thoff is still set on failure, as some callers (such as eth_get_headlen()) use it regardless of the return value.
Quoted source text, attributed separately from HOL analysis.