CVE-2026-55517

MEDIUM EPSS 8.1%
Published Jun 23, 20261w ago · Modified Jun 23, 20261w ago
4.3 CVSS 3.1
Medium
Find Similar
Published Jun 23, 2026 1w ago
Last Modified Jun 23, 2026 1w ago

Description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.5, a Deno program that opens a client WebSocket connection could be crashed by the remote server. While handling the WebSocket handshake response, Deno parsed the Sec-WebSocket-Protocol and Sec-WebSocket-Extensions response headers in a way that assumed their bytes were always printable ASCII. A response header containing non-visible-ASCII bytes (0x80-0xFF) caused a panic that aborted the entire Deno process. This vulnerability is fixed in 2.7.5.

CVSS Details

Base Score
4.3
Exploitability
2.8
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction Required
Scope Unchanged
Confidentiality None
Integrity None
Availability Low

Threat Intelligence

EPSS Exploit Probability
8.1% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-248

References 1

  • github.com https://github.com/denoland/deno/security/advisories/GHSA-x2qc-cmh9-f4hf

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.