CVE-2026-12151
HIGH 7.5Impact: 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.
Severe if exploited (CVSS 7.5), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.8%chance of exploitation in 30 days · 52nd percentile
Impact if exploited
7.5CVSS 3.1 · HIGH
- ConfidentialityNone
- IntegrityNone
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-12151/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-12151/poc.json
Affected
Products Undici Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 10.0 Extended Update Support Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Cluster Observability Operator 1.5.0 Red Hat Developer Hub 1.10 Red Hat Developer Hub 1.9 Red Hat Hardened Images Red Hat Openshift Container Platform 4.16 Red Hat Openshift Dev Spaces 3.29 Cryostat 4
Weakness (CWE)
- CWE-400: : Uncontrolled Resource Consumption
- CWE-770: : Allocation of Resources Without Limits or Throttling
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Nodejs | Undici | ≥ 6.17.0 and < 6.27.0 |
| Nodejs | Undici | ≥ 7.0.0 and < 7.28.0 |
| Nodejs | Undici | ≥ 8.0.0 and < 8.5.0 |
All CVSS metrics
- HIGH 7.5 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - HIGH 7.5 v3.1 · ADP Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - HIGH 7.5 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
Advisories
- https://github.com/nodejs/undici/security/advisories/GHSA-vxpw-j846-p89q
- https://cna.openjsf.org/security-advisories.html
- https://access.redhat.com/errata/RHSA-2026:39246
- https://access.redhat.com/errata/RHSA-2026:35842
- https://access.redhat.com/errata/RHSA-2026:35841
- https://access.redhat.com/errata/RHSA-2026:41947
- https://access.redhat.com/errata/RHSA-2026:39868
- https://access.redhat.com/errata/RHSA-2026:35892
- https://access.redhat.com/errata/RHSA-2026:35891
- https://access.redhat.com/errata/RHSA-2026:34342
- https://access.redhat.com/errata/RHSA-2026:36754
- https://access.redhat.com/errata/RHSA-2026:41929
- https://access.redhat.com/errata/RHSA-2026:38236
- https://access.redhat.com/errata/RHSA-2026:38009
- https://access.redhat.com/errata/RHSA-2026:36621
- https://access.redhat.com/errata/RHSA-2026:36820