CVE-2026-98955flow_dissector: avoid u16 truncation of skb->len when computing thoff
- —Not scoredno CVSS score yet
- 0.21%Exploitation in 30 daysEPSS · top 89% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 28 days later
· 28 days later
Published
- 7 days later
· 7 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.21% · top 89% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < 3f6000fdf8a57b9786669869af8a3e050b541bf3
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < 2c2f82b696c5e877f60ea77b7784e906a5e63014
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < d44e66f5dd99319a32e378b610af7fcf78da985a
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < d9e08836d06c84abb18470c94b12b131eaccdc7d
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < 50d0cd575cab763f833d6ac6eb6550b23a0b3dae
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < 9993e6a0ac1b5b3101ffba702cacb9f42b9909d8
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < 52efce4755a4b8b82039caa773645ffc80b25362
- affected d0c081b49137cd3200f2023c0875723be66e7ce5 – < 99bda1ecbd56905f8bd934b9cdccd3bd251192b1
- affected d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc
- affected eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1
- affected 80f327285cab6ab8e10c3ea03278add5dd99fb02
- affected 4.4.114 – < 4.5
- affected 4.9.79 – < 4.10
- affected 4.14.16 – < 4.15
- affected 4.15
- unaffected < 4.15
- unaffected 5.10.273 – ≤ 5.10.*
- unaffected 5.15.224 – ≤ 5.15.*
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.113 – ≤ 6.12.*
- unaffected 6.18.57 – ≤ 6.18.*
- unaffected 7.2.11 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References8
- https://git.kernel.org/stable/c/3f6000fdf8a57b9786669869af8a3e050b541bf3 (opens in a new tab)
- https://git.kernel.org/stable/c/2c2f82b696c5e877f60ea77b7784e906a5e63014 (opens in a new tab)
- https://git.kernel.org/stable/c/d44e66f5dd99319a32e378b610af7fcf78da985a (opens in a new tab)
- https://git.kernel.org/stable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d (opens in a new tab)
- https://git.kernel.org/stable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae (opens in a new tab)
- https://git.kernel.org/stable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8 (opens in a new tab)
- https://git.kernel.org/stable/c/52efce4755a4b8b82039caa773645ffc80b25362 (opens in a new tab)
- https://git.kernel.org/stable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-108929 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-98955)Record last updated .