CVE-2026-1526
What it is
The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive. The vulnerability exists in the PerMessageDeflate.decompress() method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 1.3% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.3% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.3% · EPSS, next 30 days
- Weakness
- CWE-409
- Record status
- Modified
Affected
- Nodejs Undici < 6.24.0
- Nodejs Undici < 7.24.0
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-1526.md and follow it. Check whether this project is affected by CVE-2026-1526. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://cna.openjsf.org/security-advisories.html
- https://github.com/nodejs/undici/security/advisories/GHSA-vrm6-8vpv-qv8q
References
- https://cna.openjsf.org/security-advisories.html
- https://datatracker.ietf.org/doc/html/rfc7692
- https://github.com/nodejs/undici/security/advisories/GHSA-vrm6-8vpv-qv8q
- https://hackerone.com/reports/3481206
- https://access.redhat.com/errata/RHSA-2026:13826
- https://access.redhat.com/errata/RHSA-2026:17789
- https://access.redhat.com/errata/RHSA-2026:21772
- https://access.redhat.com/errata/RHSA-2026:21931
- https://access.redhat.com/errata/RHSA-2026:34342
- https://access.redhat.com/errata/RHSA-2026:56431
- https://access.redhat.com/errata/RHSA-2026:5807
- https://access.redhat.com/errata/RHSA-2026:7080
- https://access.redhat.com/errata/RHSA-2026:7123
- https://access.redhat.com/errata/RHSA-2026:7302
- https://access.redhat.com/errata/RHSA-2026:7310
- https://access.redhat.com/errata/RHSA-2026:7350
- https://access.redhat.com/errata/RHSA-2026:7670
- https://access.redhat.com/errata/RHSA-2026:7675
- https://access.redhat.com/errata/RHSA-2026:7983
- https://access.redhat.com/errata/RHSA-2026:9742
- https://access.redhat.com/security/cve/CVE-2026-1526
- https://bugzilla.redhat.com/show_bug.cgi?id=2447142
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-1526.json