HighCVE-2026-109869

undici vulnerable to Denial of Service via unhandled error on excessive content-encodings (CVE-2026-109869)

Published 15.10.2026Last modified 19.10.2026Sources: Red Hat, OSV, CVE.org, Hersteller

What is affected, what to do

A flaw was found in undici. When an application sends a request to a malicious remote server, the server can return a response with excessive content encodings and immediately close the connection.

Update Undici to version 6.29.1, Undici to version 7.30.1, Undici to version 8.12.2.

Affected: Undici lt 6.23.0..6.29.1
Undici lt 7.18.0..7.30.1
Undici lt 8.0.0..8.12.2
Fixed in: Undici 6.29.1
Undici 7.30.1
Undici 8.12.2

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

7.5

Priority

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

Source: Vendor (CNA), CVSS v3

7.5

CVSS v3

Severity High on the scale from 0 to 10.

Source: Red Hat, OSV, CVE.org, Hersteller

0.3 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 27.9

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: 73.74 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: 7.5 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: 7.5
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: 0.3 %; 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: 27.9; Elevated — this CVE ranks above at least 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: 15.10.2026
CISA assessment (SSVC): Exploitation: none known · automatable · Technical impact: partial; 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-248, CWE-459

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

A flaw was found in undici. When an application sends a request to a malicious remote server, the server can return a response with excessive content encodings and immediately close the connection. Because the underlying response stream is left unhandled, this abrupt closure triggers an unhandled error that causes the application process to crash. Consequently, an attacker operating a remote server can cause a Denial of Service (DoS), terminating the application even if standard error handling is implemented.

Source: redhat_csaf, OSV (Open Source Vulnerabilities), NVD (NIST), GitHub Security Advisories, cvelistv5

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
undici	undici	`6.23.0 – < 6.29.1` `7.18.0 – < 7.30.1` `8.0.0 – < 8.12.2`	`6.29.1` `7.30.1` `8.12.2`
nodejs	undici	`8.0.0 – < 8.12.2` `7.18.0 – < 7.30.1` `6.23.0 – < 6.29.1`	`8.12.2` `7.30.1` `6.29.1`
npm	undici	`>= 6.23.0, < 6.29.1` `>= 7.18.0, < 7.30.1` `6.23.0` `>= 8.0.0, < 8.12.2` `8.0.0` `7.18.0`	`6.29.1` `7.30.1` `6.29.1` `8.12.2` `8.12.2` `7.30.1`

Vendors and products

Weakness classes (CWE)

CWE-248Uncaught Exception
Base
An exception is thrown from a function, but it is not caught.
Entry at MITRE CWE-248
CWE-459Incomplete Cleanup
Base
The product does not properly "clean up" and remove temporary or supporting resources after they have been used.
Entry at MITRE CWE-459

References & sources

github.comnodejs/undici/security/advisories/GHSA-xjj6-f33q-929cVendor advisory, web
cna.openjsf.orgsecurity-advisories.htmlVendor advisory, web
NVD (NIST)vuln/detail/CVE-2026-109869advisory
github.comnodejs/undici/commit/07ded4941b1e72afec862958c3b8ddf468f3b429web
github.comnodejs/undici/commit/1325a87dfb3492f8e87e6b0a84b3bda4e82e3436web
github.comnodejs/undici/commit/b5084c7dc239172d75c336b1cd51ddac023938a5web
github.comnodejs/undicipackage
github.comnodejs/undici/releases/tag/v6.29.1web
github.comnodejs/undici/releases/tag/v7.30.1web
github.comnodejs/undici/releases/tag/v8.12.2web

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).

19.10.2026Initial analysis by NVDNVD

Newly listed as affected:

Nodejs undici (8.0.0 – before 8.12.2; 6.23.0 – before 6.29.1; 7.18.0 – before 7.30.1)

New references:

Show 3 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Product configuration	added	—	OR cpe:2.3:a:nodejs:undici::::::node.js:: versions from (including) 8.0.0 up to (excluding) 8.12.2 cpe:2.3:a:nodejs:undici::::::node.js:: versions from (including) 6.23.0 up to (excluding) 6.29.1 cpe:2.3:a:nodejs:undici::::::node.js:: versions from (including) 7.18.0 up to (excluding) 7.30.1
Reference type	added	—	openjs: https://cna.openjsf.org/security-advisories.html Types: Vendor Advisory
Reference type	added	—	openjs: https://github.com/nodejs/undici/security/advisories/GHSA-xjj6-f33q-929c Types: Vendor Advisory

Source identifier: nvd@nist.gov

16.10.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: none known, automatable: yes

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	added	—	{"id":"CVE-2026-109869","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T20:05:44.033842Z"}

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

15.10.2026ReceivedOpenJS Foundation

CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type: CWE-248, CWE-459

Description added or changed

New references:

Show 7 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	undici is an HTTP client library for Node.js. In versions 6.23.0 through 6.29.0, 7.18.0 through 7.30.0, and 8.0.0 through 8.12.1, its fetch() implementation crashes the Node.js process when a malicious server returns a response with more than five content codings and closes the connection before sending the body. undici rejects such responses because of a content-encoding limit, but it created the internal response stream before that check and returned without attaching an error listener or aborting the request, so the early close surfaces a content-length mismatch on the orphaned stream, which Node.js treats as an unhandled error and terminates the process. A remote, unauthenticated server can trigger this with a single response, even when the application correctly catches the fetch() rejection, resulting in a denial of service. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, and users should upgrade to one of those versions or later. There is no workaround.
CVSS	added	—	AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness type (CWE)	added	—	CWE-248
Weakness type (CWE)	added	—	CWE-459
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/109xxx/CVE-2026-109869.json">CVE-2026-109869</a>
Reference	added	—	https://cna.openjsf.org/security-advisories.html
Reference	added	—	https://github.com/nodejs/undici/security/advisories/GHSA-xjj6-f33q-929c

Source identifier: ce714d77-add3-4f53-aff5-83d477b104bb

Embed badge

Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

<a href="https://intel.neosec.eu/en/cve/CVE-2026-109869"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-109869.svg?lang=en" alt="CVE-2026-109869 – NEOSEC Intel" height="20"></a>