CyberSecBulletin
CVE-2026-2229NVD status: Modified

undici: Uncaught Exception

Published Updated By the CyberSecBulletin desk

CVE-2026-2229 is a high-severity uncaught exception vulnerability in undici, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected undici versions: < 6.24.0; 7.0.0 < 7.24.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1% chance of exploitation within 30 days, higher than 63% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of undici you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on cna.openjsf.org for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Undiciundici< 6.24.0; 7.0.0 < 7.24.0Not stated
Red HatCryostat 4 on RHEL 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 10Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 10.0 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.6 Extended Update SupportNot specified in the recordNot stated
Red HatCluster Observability Operator 1.5.0Not specified in the recordNot stated
Red HatRed Hat Developer Hub 1.8Not specified in the recordNot stated
Red HatRed Hat Developer Hub 1.9Not specified in the recordNot stated
Red HatRed Hat OpenShift AI 2.16Not specified in the recordNot stated
Red HatRed Hat Openshift Data Foundation 4.18Not specified in the recordNot stated
Red HatRed Hat OpenShift Dev Spaces 3.28Not specified in the recordNot stated
Red HatRed Hat OpenShift Pipelines 1.2Not specified in the recordNot stated
Red HatOpenShift LightspeedNot specified in the recordNot stated
Red HatOpenShift PipelinesNot specified in the recordNot stated
Red HatRed Hat Developer HubNot specified in the recordNot stated
Red HatRed Hat JBoss Enterprise Application Platform 8Not specified in the recordNot stated
Red HatRed Hat JBoss Enterprise Application Platform Expansion PackNot specified in the recordNot stated
Red HatRed Hat OpenShift AI (RHOAI)Not specified in the recordNot stated
Red HatRed Hat OpenShift Dev SpacesNot specified in the recordNot stated
Red HatSelf-service automation portal 2Not specified in the recordNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighCNA
CVSS 3.17.5HighCNA

Official description

ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination. The vulnerability exists because: * The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15 * The createInflateRaw() call is not wrapped in a try-catch block * The resulting exception propagates up through the call stack and crashes the Node.js process

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Uncaught Exception

An exception is thrown from a function, but it is not caught.

How developers prevent this class of flaw

  • The choice between a language which has named or unnamed exceptions needs to be done. While unnamed exceptions exacerbate the chance of not properly dealing with an exception, named exceptions suffer from the up call version of the weak base class problem.
  • A language can be used which requires, at compile time, to catch all serious exceptions. However, one must make sure to use the most current version of the API as new exceptions could be added.
  • Catch all relevant exceptions. This is the recommended solution. Ensure that all exceptions are handled in such a way that you can be sure of the state of your system at any given moment.

More Uncaught Exception vulnerabilities (CWE-248)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in undici

All undici vulnerabilities

Recent Uncaught Exception vulnerabilities

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