LowCVE-2026-98955

Linux Kernel: security vulnerability (CVE-2026-98955)

Published 23.10.2026Last modified 30.10.2026Sources: BSI, Msrc Update Guide, CVE.org

What is affected, what to do

The available sources name no fixed version. Check the vendor guidance in the references below.

Conflicting version data — version display is hidden until the data is resolved.

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Metrics

3.4

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: Vendor (CNA), CVSS v3

3.4

CVSS v3

Severity Low on the scale from 0 to 10.

Source: BSI, Msrc Update Guide, CVE.org

0.2 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 7.3

Show all metrics

Severity: Low
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 47.43 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 3.4 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 3.4
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.2 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 7.3; Low — this CVE sits in the lower 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 23.10.2026

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

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.

Source: BSI CSAF, BSI WID Portal, Microsoft Security Update Guide, cvelistv5, NVD (NIST)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Linux	Linux	`6.19 – < 7.2.11` `4.14.16 – < 4.15` `5.11 – < 5.15.224` `5.16 – < 6.1.191` `6.7 – < 6.12.113` `4.15 – < 5.10.273` `4.9.79 – < 4.10` `—` `6.13 – < 6.18.57` `4.4.114 – < 4.5` `6.2 – < 6.6.160`	`7.2.11` `4.15` `5.15.224` `6.1.191` `6.12.113` `5.10.273` `4.10` `7.3` `6.18.57` `4.5` `6.6.160`

Vendors and products

Linux Linux

References & sources

git.kernel.orgstable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae
git.kernel.orgstable/c/52efce4755a4b8b82039caa773645ffc80b25362
git.kernel.orgstable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8
git.kernel.orgstable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1
git.kernel.orgstable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d
git.kernel.orgstable/c/2c2f82b696c5e877f60ea77b7784e906a5e63014
git.kernel.orgstable/c/3f6000fdf8a57b9786669869af8a3e050b541bf3
git.kernel.orgstable/c/d44e66f5dd99319a32e378b610af7fcf78da985a

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

30.10.2026Record modifiedLinux

New references:

Show 4 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/98xxx/CVE-2026-98955.json">CVE-2026-98955</a>
Reference	added	—	https://git.kernel.org/stable/c/2c2f82b696c5e877f60ea77b7784e906a5e63014
Reference	added	—	https://git.kernel.org/stable/c/3f6000fdf8a57b9786669869af8a3e050b541bf3
Reference	added	—	https://git.kernel.org/stable/c/d44e66f5dd99319a32e378b610af7fcf78da985a

Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

23.10.2026ReceivedLinux

Description added or changed

New references:

and 1 more reference

Show 7 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	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.
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/98xxx/CVE-2026-98955.json">CVE-2026-98955</a>
Reference	added	—	https://git.kernel.org/stable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae
Reference	added	—	https://git.kernel.org/stable/c/52efce4755a4b8b82039caa773645ffc80b25362
Reference	added	—	https://git.kernel.org/stable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8
Reference	added	—	https://git.kernel.org/stable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1
Reference	added	—	https://git.kernel.org/stable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d

Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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