HighCVE-2026-31630

Linux Kernel: Stack-based Buffer Overflow (CVE-2026-31630)

Published 24.04.2026Last modified 21.10.2026Sources: Debian LTS, Siemens ProductCERT, Ubuntu, BSI, Msrc Update Guide, CVE.org, EUVD

What is affected, what to do

Update Linux Kernel to version 5.10.258, Linux Kernel to version 5.15.209, Linux Kernel to version 6.1.175.

Affected: Linux Kernel lt 4.9..5.10.258
Linux Kernel lt 5.11..5.15.209
Linux Kernel lt 5.16..6.1.175
Linux Kernel lt 6.2..6.6.160
Linux Kernel lt 6.7..6.12.114
Linux Kernel lt 6.13..6.18.23
Linux Kernel lt 6.19..6.19.13
Linux Kernel lt 6.20..7.0
Fixed in: Linux Kernel 5.10.258
Linux Kernel 5.15.209
Linux Kernel 6.1.175
Linux Kernel 6.6.160
Linux Kernel 6.12.114
Linux Kernel 6.18.23
Linux Kernel 6.19.13
Linux Kernel 7.0

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Metrics

7.8

Priority

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

Source: NVD, CVSS v3

7.8

CVSS v3

Severity High on the scale from 0 to 10.

Source: Debian LTS, Siemens ProductCERT, Ubuntu, BSI, Msrc Update Guide, CVE.org, EUVD

0.2 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 7.0

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: 55.96 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: 7.8 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: 7.8
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: 7.0; 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: 24.04.2026
CISA assessment (SSVC): Exploitation: none known · not automatable · Technical impact: total; Source: CISA Vulnrichment, as of 16 October 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-121

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:

rxrpc: proc: size address buffers for %pISpc output

The AF_RXRPC procfs helpers format local and remote socket addresses into fixed 50-byte stack buffers with "%pISpc".

That is too small for the longest current-tree IPv6-with-port form the formatter can produce. In lib/vsprintf.c, the compressed IPv6 path uses a dotted-quad tail not only for v4mapped addresses, but also for ISATAP addresses via ipv6_addr_is_isatap().

As a result, a case such as

is possible with the current formatter. That is 50 visible characters, so 51 bytes including the trailing NUL, which does not fit in the existing char[50] buffers used by net/rxrpc/proc.c.

Size the buffers from the formatter's maximum textual form and switch the call sites to scnprintf().

Changes since v1:

correct the changelog to cite the actual maximum current-tree case explicitly
frame the proof around the ISATAP formatting path instead of the earlier mapped-v4 example

Source: Debian LTS Advisories, siemens_advisory, Ubuntu Security Notices, BSI WID Portal, BSI CSAF, Microsoft Security Update Guide, NVD (NIST), cvelistv5, ENISA EUVD, CVE.org (MITRE)

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	`6.7 – < 6.12.114` `5.16 – < 6.1.175` `5.11 – < 5.15.209` `6.13 – < 6.18.23` `6.19 – < 6.19.13` `6.2 – < 6.6.160` `6.20 – < 7.0` `4.9 – < 5.10.258`	`6.12.114` `6.1.175` `5.15.209` `6.18.23` `6.19.13` `6.6.160` `7.0` `5.10.258`
Siemens	SIMATIC S7	`1500 TM MFP V1.1.1 GNU/Linux subsystem`	—

Vendors and products

Affected operating systems

Affected operating systems

Linux	debian	linux	`bookworm`
Linux	debian	linux	`bullseye`
Linux	debian	linux-6.1	`bullseye`
Linux	linux	linux_kernel	`4.9`
Linux	linux	linux_kernel	`7.0`
Linux	linux	linux_kernel	—

Weakness classes (CWE)

CWE-121Stack-based Buffer Overflow
Variant
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Entry at MITRE CWE-121

References & sources

git.kernel.orgstable/c/db297c78ce537c9ac96f0eda9b25ad72c8caefa9euvd, Patch
git.kernel.orgstable/c/10ebed83f9f6414af4e85bc85ffaeda7effdd874euvd, Patch
git.kernel.orgstable/c/a44ce6aa2efb61fe44f2cfab72bb01544bbca272euvd, Patch
git.kernel.orgstable/c/386c86412608d3449006a318a662cbcd6ca1f668
git.kernel.orgstable/c/235b2115de892eab2e107a42efa7a4347baaa80b
git.kernel.orgstable/c/625af53a1564e31bb2df9adc3739df46137f46c1
Siemens ProductCERTproductcert/html/ssa-784472.html
git.kernel.orgstable/c/808a34cdbe8ce336c202d8ea6d5e48496764dc37
git.kernel.orgstable/c/a6042b8066b24dbcc7945616a157d4d43e463668

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).

21.10.2026Record modifiedLinux

New references:

Show 3 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/2026/31xxx/CVE-2026-31630.json">CVE-2026-31630</a>
Reference	added	—	https://git.kernel.org/stable/c/808a34cdbe8ce336c202d8ea6d5e48496764dc37
Reference	added	—	https://git.kernel.org/stable/c/a6042b8066b24dbcc7945616a157d4d43e463668

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

19.10.2026Record modifiedCISA ADP
Weakness type: CWE-121
Show the original change
Individual changes of this event as published by NVD
Type Action Before After
Weakness type (CWE) added
—
CWE-121
Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Individual changes of this event as published by NVD
Type	Action	Before	After
Weakness type (CWE)	added	—	CWE-121

16.10.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: none known, automatable: no

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	added	—	{"id":"CVE-2026-31630","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:11:18.108954Z"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

15.10.2026Record modifiedLinux

New references:

and 2 more references

Show 15 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://git.kernel.org/stable/c/10ebed83f9f6414af4e85bc85ffaeda7effdd874
Reference	added	—	https://git.kernel.org/stable/c/235b2115de892eab2e107a42efa7a4347baaa80b
Reference	added	—	https://git.kernel.org/stable/c/386c86412608d3449006a318a662cbcd6ca1f668
Reference	added	—	https://git.kernel.org/stable/c/625af53a1564e31bb2df9adc3739df46137f46c1
Reference	added	—	https://git.kernel.org/stable/c/a44ce6aa2efb61fe44f2cfab72bb01544bbca272
Reference	added	—	https://git.kernel.org/stable/c/db297c78ce537c9ac96f0eda9b25ad72c8caefa9
Reference	removed	https://git.kernel.org/stable/c/10ebed83f9f6414af4e85bc85ffaeda7effdd874	—
Reference	removed	https://git.kernel.org/stable/c/235b2115de892eab2e107a42efa7a4347baaa80b	—
Reference	removed	https://git.kernel.org/stable/c/386c86412608d3449006a318a662cbcd6ca1f668	—
Reference	removed	https://git.kernel.org/stable/c/625af53a1564e31bb2df9adc3739df46137f46c1	—
Reference	removed	https://git.kernel.org/stable/c/a44ce6aa2efb61fe44f2cfab72bb01544bbca272	—
Reference	removed	https://git.kernel.org/stable/c/db297c78ce537c9ac96f0eda9b25ad72c8caefa9	—
Reference type	removed	https://git.kernel.org/stable/c/10ebed83f9f6414af4e85bc85ffaeda7effdd874 Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/a44ce6aa2efb61fe44f2cfab72bb01544bbca272 Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/db297c78ce537c9ac96f0eda9b25ad72c8caefa9 Types: Patch	—

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

15.10.2026Record modifiedSiemens ADP

New references:

https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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/2026/31xxx/CVE-2026-31630.json">CVE-2026-31630</a>
Reference	added	—	https://cert-portal.siemens.com/productcert/html/ssa-784472.html

Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

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