Linux Kernel: security vulnerability (CVE-2026-46321)
Published Last modified Sources: SUSE, Debian LTS, Ubuntu, Siemens ProductCERT, Debian, BSI, CVE.org, Msrc Update Guide
What is affected, what to do
In the Linux kernel, the following vulnerability has been resolved: tun: free page on short-frame rejection in tun_xdp_one() tun_xdp_one() returns -EINVAL on a frame shorter than ETH_HLEN without freeing the page that vhost_net_build_xdp() allocated for it. tun_sendmsg() discards that -EINVAL and still returns total_len, so vhost_tx_batch() takes the success path and never frees the page; each short frame in a batch leaks one page-frag chunk. A local process that can open /dev/net/tun and /dev/vhost-net can hit this path: it attaches a tun/tap device as the vhost-net backend and feeds TX descriptors whose length minus the virtio-net header is below ETH_HLEN.
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
7.1
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v3
7.1
CVSS v3
Severity High on the scale from 0 to 10.
Source: SUSE, Debian LTS, Ubuntu, Siemens ProductCERT, Debian, BSI, CVE.org, Msrc Update Guide
0.1 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 2.8
Show all metrics
- Severity
- High
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- 54.22 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- 7.1 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- 7.1
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- 0.1 %
- 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- 2.8
- 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
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- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
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: tun: free page on short-frame rejection in tun_xdp_one() tun_xdp_one() returns -EINVAL on a frame shorter than ETH_HLEN without freeing the page that vhost_net_build_xdp() allocated for it. tun_sendmsg() discards that -EINVAL and still returns total_len, so vhost_tx_batch() takes the success path and never frees the page; each short frame in a batch leaks one page-frag chunk. A local process that can open /dev/net/tun and /dev/vhost-net can hit this path: it attaches a tun/tap device as the vhost-net backend and feeds TX descriptors whose length minus the virtio-net header is below ETH_HLEN. Each kick leaks the page-frag chunks for that batch, and a tight submission loop exhausts host memory and triggers an OOM panic. Free the page before returning -EINVAL, matching the XDP-program error path in the same function.
Source: suse_csaf, Debian LTS Advisories, Ubuntu Security Notices, siemens_advisory, Debian Security Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), CVE.org (MITRE), Microsoft Security Update Guide
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Linux | Linux |
|
|
| Siemens | SIMATIC S7 |
|
|
Vendors and products
Affected operating systems
| Linux | debian | linux | bookworm |
| Linux | debian | linux | bullseye |
| Linux | debian | linux | trixie |
| Linux | debian | linux-6.1 | bullseye |
| Linux | ubuntu | linux-oracle-7.0 | noble |
| Linux | linux | linux_kernel | 7.1 |
| Linux | linux | linux_kernel | — |
References & sources
- git.kernel.orgstable/c/69863ff2720a0e9871f1a5710f2a33a94217fee0
- git.kernel.orgstable/c/37a1c268c2c8090bf4dc552d732bd23ba36f8eb0
- git.kernel.orgstable/c/98c67be9eb9de72465a071949e84a3cdb8fab5a3
- git.kernel.orgstable/c/f4feb1e20058e407cb00f45aff47f5b7e19a6bbf
- git.kernel.orgstable/c/0a6f46a9332ad6958992d64d3b3a81a80b2ca940
- git.kernel.orgstable/c/0e8211fcf9426f5adddf32516ba0f400ceb9544d
- git.kernel.orgstable/c/e915445942af6dcea628bf66d6241641201a0c41
- git.kernel.orgstable/c/5b34f9e4fe2f203724a6e893d6df0316b9670057
- Siemens ProductCERTproductcert/html/ssa-784472.html
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).
Record modifiedLinux
New references:- https://git.kernel.org/stable/c/0a6f46a9332ad6958992d64d3b3a81a80b2ca940
- https://git.kernel.org/stable/c/0e8211fcf9426f5adddf32516ba0f400ceb9544d
- https://git.kernel.org/stable/c/37a1c268c2c8090bf4dc552d732bd23ba36f8eb0
- https://git.kernel.org/stable/c/5b34f9e4fe2f203724a6e893d6df0316b9670057
and 4 more references
Show 24 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/0a6f46a9332ad6958992d64d3b3a81a80b2ca940Reference added —https://git.kernel.org/stable/c/0e8211fcf9426f5adddf32516ba0f400ceb9544dReference added —https://git.kernel.org/stable/c/37a1c268c2c8090bf4dc552d732bd23ba36f8eb0Reference added —https://git.kernel.org/stable/c/5b34f9e4fe2f203724a6e893d6df0316b9670057Reference added —https://git.kernel.org/stable/c/69863ff2720a0e9871f1a5710f2a33a94217fee0Reference added —https://git.kernel.org/stable/c/98c67be9eb9de72465a071949e84a3cdb8fab5a3Reference added —https://git.kernel.org/stable/c/e915445942af6dcea628bf66d6241641201a0c41Reference added —https://git.kernel.org/stable/c/f4feb1e20058e407cb00f45aff47f5b7e19a6bbfReference removed https://git.kernel.org/stable/c/0a6f46a9332ad6958992d64d3b3a81a80b2ca940—Reference removed https://git.kernel.org/stable/c/0e8211fcf9426f5adddf32516ba0f400ceb9544d—Reference removed https://git.kernel.org/stable/c/37a1c268c2c8090bf4dc552d732bd23ba36f8eb0—Reference removed https://git.kernel.org/stable/c/5b34f9e4fe2f203724a6e893d6df0316b9670057—Reference removed https://git.kernel.org/stable/c/69863ff2720a0e9871f1a5710f2a33a94217fee0—Reference removed https://git.kernel.org/stable/c/98c67be9eb9de72465a071949e84a3cdb8fab5a3—Reference removed https://git.kernel.org/stable/c/e915445942af6dcea628bf66d6241641201a0c41—Reference removed https://git.kernel.org/stable/c/f4feb1e20058e407cb00f45aff47f5b7e19a6bbf—Reference type removed https://git.kernel.org/stable/c/0a6f46a9332ad6958992d64d3b3a81a80b2ca940 Types: Patch—Reference type removed https://git.kernel.org/stable/c/0e8211fcf9426f5adddf32516ba0f400ceb9544d Types: Patch—Reference type removed https://git.kernel.org/stable/c/37a1c268c2c8090bf4dc552d732bd23ba36f8eb0 Types: Patch—Reference type removed https://git.kernel.org/stable/c/5b34f9e4fe2f203724a6e893d6df0316b9670057 Types: Patch—Reference type removed https://git.kernel.org/stable/c/69863ff2720a0e9871f1a5710f2a33a94217fee0 Types: Patch—Reference type removed https://git.kernel.org/stable/c/98c67be9eb9de72465a071949e84a3cdb8fab5a3 Types: Patch—Reference type removed https://git.kernel.org/stable/c/e915445942af6dcea628bf66d6241641201a0c41 Types: Patch—Reference type removed https://git.kernel.org/stable/c/f4feb1e20058e407cb00f45aff47f5b7e19a6bbf Types: Patch—Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record modifiedSiemens ADP
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/46xxx/CVE-2026-46321.json">CVE-2026-46321</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Record modifiedLinux
New references:Show 5 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/0a6f46a9332ad6958992d64d3b3a81a80b2ca940Reference added —https://git.kernel.org/stable/c/0e8211fcf9426f5adddf32516ba0f400ceb9544dReference added —https://git.kernel.org/stable/c/5b34f9e4fe2f203724a6e893d6df0316b9670057Reference added —https://git.kernel.org/stable/c/e915445942af6dcea628bf66d6241641201a0c41Affected versions (publisher) changed Linux, LinuxLinux, LinuxSource identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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<a href="https://intel.neosec.eu/en/cve/CVE-2026-46321"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-46321.svg?lang=en" alt="CVE-2026-46321 – NEOSEC Intel" height="20"></a>