Review reviewHigh

CVE-2026-2229

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

ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeErro...

CVSS: 7.5
EPSS: 0.87%
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 probability0.87%

Technical severityCVSS 7.5

Vulnerability overview

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
Identify
Confirm that undici undici, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
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-1284, CWE-248