GHSA-W67G-5RQW-F597

Vulnerability from github – Published: 2026-08-24 21:00 – Updated: 2026-08-24 21:00
VLAI
Summary
Gorilla WebSocket Uses Cryptographically Weak PRNG for WebSocket Mask Key
Details

gorilla/websocket used math/rand (cryptographically weak pseudo-random number generator) to generate WebSocket frame mask keys prior to commit d67f4185. WebSocket masking keys MUST be unpredictable to prevent frame content injection attacks. math/rand produces deterministic output when seeded with a known value, enabling an attacker to predict or recover mask keys and inject content into WebSocket connections.

Type: Use of Cryptographically Weak Pseudo-Random Number Generator Fix: Replaced math/rand with crypto/rand (commit d67f4185, released in v1.5.3) Credit: bounty-hunter v6.0 silent-fix detection

Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/gorilla/websocket"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.5.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-338"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-24T21:00:54Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "gorilla/websocket used `math/rand` (cryptographically weak pseudo-random number generator) to generate WebSocket frame mask keys prior to commit d67f4185. WebSocket masking keys MUST be unpredictable to prevent frame content injection attacks. math/rand produces deterministic output when seeded with a known value, enabling an attacker to predict or recover mask keys and inject content into WebSocket connections.\n\n**Type:** Use of Cryptographically Weak Pseudo-Random Number Generator\n**Fix:** Replaced math/rand with crypto/rand (commit d67f4185, released in v1.5.3)\n**Credit:** bounty-hunter v6.0 silent-fix detection",
  "id": "GHSA-w67g-5rqw-f597",
  "modified": "2026-08-24T21:00:54Z",
  "published": "2026-08-24T21:00:54Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/canolgun-commits/websocket/security/advisories/GHSA-w67g-5rqw-f597"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gorilla/websocket/commit/d67f41855da42d7bccd9ef050c49f7e54e783b95"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/canolgun-commits/websocket"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gorilla/websocket/releases/tag/v1.5.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Gorilla WebSocket Uses Cryptographically Weak PRNG for WebSocket Mask Key"
}



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