Summaryinfo

A vulnerability was found in undici. It has been rated as problematic. The affected element is the function decompress of the component WebSocket Handler. Performing a manipulation results in data amplification. This vulnerability was named CVE-2026-1526. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in undici. It has been classified as problematic. This affects the function decompress of the component WebSocket Handler. The manipulation with an unknown input leads to a data amplification vulnerability. CWE is classifying the issue as CWE-409. The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. This is going to have an impact on availability. The summary by CVE 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.

The weakness was presented by HO9. It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-1526 since 01/28/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 302064 (Linux Distros Unpatched Vulnerability : CVE-2026-1526), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.24.0: 7.24.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (302064) and CERT Bund (WID-SEC-2026-0933). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• IBM App Connect Enterprise

Productinfo

Name

• undici

Version

• 5.7.1
• 5.8.0
• 5.8.1
• 5.8.2
• 5.19.1
• 5.26.2
• 5.28.4
• 5.28.5
• 5.29.0
• 6.0.0
• 6.6.1
• 6.11.0
• 6.11.1
• 6.19.2
• 6.21.0
• 6.21.1
• 6.21.2
• 6.23.0

CPE 2.3info

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CPE 2.2info

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