CVE-2026-98955: flow_dissector: avoid u16 truncation of skb->len when computing thoff
Noroxi assessment
Priority: Monitor (action score 0/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
- Fixed version: Linux Linux 2c2f82b696c5e877f60ea77b7784e906a5e63014, 3f6000fdf8a57b9786669869af8a3e050b541bf3, 4.10; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 2c2f82b696c5e877f60ea77b7784e906a5e63014, 3f6000fdf8a57b9786669869af8a3e050b541bf3, 4.10; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- Oct 23, 2026
- Updated
- Oct 30, 2026
- EPSS
- 0.1% · 7th percentile
- CWE
- —
Report tools
Action score
0
Monitor
Low priority for now.
- CVSS
- 0 / 40 · —
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.1%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc, eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1, 80f327285cab6ab8e10c3ea03278add5dd99fb02, 4.15affected
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before 3f6000fdf8a57b9786669869af8a3e050b541bf3affected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before 2c2f82b696c5e877f60ea77b7784e906a5e63014affected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before d44e66f5dd99319a32e378b610af7fcf78da985aaffected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before d9e08836d06c84abb18470c94b12b131eaccdc7daffected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before 50d0cd575cab763f833d6ac6eb6550b23a0b3daeaffected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before 9993e6a0ac1b5b3101ffba702cacb9f42b9909d8affected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before 52efce4755a4b8b82039caa773645ffc80b25362affected · git
- d0c081b49137cd3200f2023c0875723be66e7ce5 and later · before 99bda1ecbd56905f8bd934b9cdccd3bd251192b1affected · git
- 4.4.114 and later · before 4.5affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | linux | from 0 | — |
| Debian:13 | linux | before 6.12.113-1 | 6.12.113-1 |
| Debian:14 | linux | before 7.2.11-1 | 7.2.11-1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation40Plan
- CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment40Plan
- CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()40Plan
Published before and after this one in the same product
- ← EarlierCVE-2026-98953Oct 23, 2026 · devlink: fix devlink_rel reference leak when notify work is pending0Monitor
- ← EarlierCVE-2026-98954Oct 23, 2026 · net: always dissect GSO packets in __virtio_net_hdr_to_skb()0Monitor
- Later →CVE-2026-98956Oct 23, 2026 · ASoC: adau1372: allow sleepy powerdown GPIOs0Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 2c2f82b696c5e877f60ea77b7784e906a5e63014 | Vendor (CNA) |
| Linux Linux | 3f6000fdf8a57b9786669869af8a3e050b541bf3 | Vendor (CNA) |
| Linux Linux | 4.10 | Vendor (CNA) |
| Linux Linux | 4.15 | Vendor (CNA) |
| Linux Linux | 4.5 | Vendor (CNA) |
| Linux Linux | 50d0cd575cab763f833d6ac6eb6550b23a0b3dae | Vendor (CNA) |
| Linux Linux | 52efce4755a4b8b82039caa773645ffc80b25362 | Vendor (CNA) |
| Linux Linux | 9993e6a0ac1b5b3101ffba702cacb9f42b9909d8 | Vendor (CNA) |
| Linux Linux | 99bda1ecbd56905f8bd934b9cdccd3bd251192b1 | Vendor (CNA) |
| Linux Linux | d44e66f5dd99319a32e378b610af7fcf78da985a | Vendor (CNA) |
| Linux Linux | d9e08836d06c84abb18470c94b12b131eaccdc7d | Vendor (CNA) |
| azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 | Release Notes | Microsoft (MSRC) |
| azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 | Release Notes | Microsoft (MSRC) |
| debian:linux | 6.12.113-1 · Debian:13 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- Fix recordedsame day
- TodayNov 4, 2026+12 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-1390 · Oct 26, 2026(Linux Kernel Güvenlik Bildirimi)
Technical details
No CVSS vector for this record, so attack conditions can't be derived.
Weakness class (CWE)
—
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Exploit maturity— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (7 more)Show less
- git.kernel.org/stable/c/3f6000fdf8a57b9786669869af8a3e050b541bf3
- git.kernel.org/stable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae
- git.kernel.org/stable/c/52efce4755a4b8b82039caa773645ffc80b25362
- git.kernel.org/stable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8
- git.kernel.org/stable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1
- git.kernel.org/stable/c/d44e66f5dd99319a32e378b610af7fcf78da985a
- git.kernel.org/stable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d
Vendor advisories and official records. Exploit/PoC links are deliberately left out.