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CVE-2026-12151

36
FAUCET Score

Impact: The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service. Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint. All releases starting at undici 6.17.0 are affected. Patches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade.

First published: Jun 17, 2026Last modified: Jun 17, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 6.17.0, < 6.27.0CPE matchmatch criteria
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
>= 7.0.0, < 7.28.0CPE matchmatch criteria
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
>= 8.0.0, < 8.5.0CPE matchmatch criteria
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.79%
Probability of exploitation in next 30 days
EPSS Percentile
52.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0079 is in the 28th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

npmpatch availablevia ghsa
Product: undiciFixed in: 6.27.0
npmpatch availablevia ghsa
Product: undiciFixed in: 7.28.0
npmpatch availablevia ghsa
Product: undiciFixed in: 8.5.0
github_advisoryvendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

npmGHSA-vxpw-j846-p89qhigh

undici WebSocket client vulnerable to denial of service via fragment count bypass

Jun 19, 2026

References

access.redhat.com / errata/RHSA-2026:34342
access.redhat.com / errata/RHSA-2026:35841
access.redhat.com / errata/RHSA-2026:35842
access.redhat.com / errata/RHSA-2026:35891
access.redhat.com / errata/RHSA-2026:35892
access.redhat.com / errata/RHSA-2026:36621
access.redhat.com / errata/RHSA-2026:36754
access.redhat.com / errata/RHSA-2026:36820
access.redhat.com / errata/RHSA-2026:38009
access.redhat.com / errata/RHSA-2026:38236
access.redhat.com / errata/RHSA-2026:39246
access.redhat.com / errata/RHSA-2026:39868
access.redhat.com / errata/RHSA-2026:41929
access.redhat.com / errata/RHSA-2026:41947
access.redhat.com / security/cve/CVE-2026-12151
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-12151.json
cna.openjsf.org / security-advisories.html
Vendor Advisory
github.com / nodejs/undici/security/advisories/GHSA-vxpw-j846-p89q
Vendor Advisory