CVE-2026-85024: undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the i

Q: How do I fix CVE-2026-85024?

undici: upgrade to 6.28.1, 7.29.1, 8.10.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-85024 being exploited?

CVE-2026-85024 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-85024 affect?

CVE-2026-85024 affects undici. Severity is medium (CVSS 5.9). undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed

Q: How urgent is CVE-2026-85024?

Priority 34/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2026-85024 is a medium-severity flaw (CVSS 5.9) affecting undici. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed payload that crosses the built-in 128 MiB decompressed-payload limit and then contains a malformed DEFLATE byte, the inflate stream emits a data error with no listener attached, which Node.js treats as a fatal

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 65%)
CISA exploited list	No
Weakness	CWE-248
Published	2026-09-04
Last modified	2026-09-16

Publisher (CNA): openjs · Vendor: nodejs

Last updated 2026-09-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-04 17:17 UTCPublished CVE record published
2026-09-16 20:41 UTCUpdated Record last modified

nodejs undici UPGRADE

Affected: >= 6.25.0 and < 6.28.1 · >= 7.28.0 and < 7.29.1 · >= 8.1.0 and < 8.10.2

Fixed in: 6.28.1, 7.29.1, 8.10.2

Safe to downgrade to: a release before 6.25.0

1. Check installed version

npm ls undici

2. UPGRADE to 6.28.1

npm install undici@">=6.28.1"

3. If no update is available yet, DOWNGRADE to a release before 6.25.0

npm view undici versions npm install undici@"<6.25.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-85024?

undici: upgrade to 6.28.1, 7.29.1, 8.10.2. Exact commands for each OS are on this page.

Is CVE-2026-85024 being exploited?

CVE-2026-85024 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-85024 affect?

CVE-2026-85024 affects undici. Severity is medium (CVSS 5.9). undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed

How urgent is CVE-2026-85024?

Priority 34/100. Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities · zlib vulnerabilities

Related CVEs

CVE-2026-109855 HIGH 7.5 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109383 HIGH 7.4 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109829 HIGH 7.4 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109841 MEDIUM 5.9 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109869 HIGH 7.5 UPGRADE undici is an HTTP client library for Node.js

References

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