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Review reviewHigh

CVE-2026-1526

undici undici, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10

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 PerMess...

CVSS
7.5
EPSS
1.15%
63.7% percentile
CISA KEV
Not listed
Published
2026.03.13
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability1.15%
Technical severityCVSS 7.5

Vulnerability overview

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 PerMess...

Affected product and versions

Product
undici undici, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10
Affected versions
>= < 6.24.0, 7.0.0 < 7.24.0, < 6.24.0, >= 7.0.0 < 7.24.0
Fixed versions
6.24.0, 7.24.0

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that undici undici, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
CWE-409, CWE-770