{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.9"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "cf198fcddc9230f06ed39f974eba0ce076b85cda"
            },
            {
              "fixed": "8763f914472fc83652babda708bed5c8ef287004"
            }
          ],
          "repo": "https://github.com/facelessuser/soupsieve",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-j934-xhv5-fg8f"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-1333",
      "CWE-400"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85999.json"
  },
  "details": "Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.9, selector_iter in src/soupsieve/css_parser.py trims the raw selector with RE_WS_END, an end-anchored WSC whitespace-and-comment expression used with search(), so the regular expression engine retries a greedy scan at every starting offset. An attacker-controlled valid selector containing a long internal whitespace run, or a selector containing a long CSS comment run followed by another token, causes quadratic CPU work before tokenization. User-controlled selectors can reach the path through soupsieve.compile() and BeautifulSoup.select(), while applications using only hard-coded selectors are unaffected. This root cause is separate from the IDENTIFIER and VALUE backtracking vulnerability because the cost occurs in RE_WS_END.search during trimming rather than token matching. The resulting CPU consumption can hold the Python GIL, exhaust workers, and stall a service without causing memory corruption or code execution. The issue is fixed in version 2.9.",
  "id": "CVE-2026-85999",
  "modified": "2026-09-19T03:30:49.498632067Z",
  "published": "2026-09-17T15:23:37.457Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/facelessuser/soupsieve/releases/tag/2.9"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85999.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/facelessuser/soupsieve/security/advisories/GHSA-j934-xhv5-fg8f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85999"
    },
    {
      "type": "FIX",
      "url": "https://github.com/facelessuser/soupsieve/commit/cf198fcddc9230f06ed39f974eba0ce076b85cda"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Soup Sieve: Polynomial-time ReDoS (O(n²)) in the whitespace/comment trimming regex `RE_WS_END` (triggers on VALID selectors)"
}