GHSA-wjmf-p669-5m5p

Source

https://github.com/advisories/GHSA-wjmf-p669-5m5p

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-wjmf-p669-5m5p/GHSA-wjmf-p669-5m5p.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-wjmf-p669-5m5p

Aliases

Published

2026-08-28T18:43:02Z

Modified

2026-09-10T12:25:43Z

Severity

7.1 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator

Summary

Protego has exponential backtracking ReDoS in robots.txt URL wildcard matching

Details

Problem description

Protego constructs regular expressions to match URLs against robots.txt Allow: and Disallow: directives, see protego._urlpattern._URLPattern._prepare_pattern_for_regex(). Every * in the directive value is translated into a lazy .*? regex piece, thus a specially crafted directive value with many asterisks may produce a regex that freezes the parser due to exponential backtracking.

Impact

Parsing a specially crafted robots.txt with protego.Protego.parse() and then trying to match an URL with protego.Protego.can_fetch() results in the latter call not returning for a period dependent on the length of the URL.

Proof of concept

from protego import Protego

robotstxt = f"""
User-agent: *
Disallow: /{"*1" * 12}*Z
"""
rp = Protego.parse(robotstxt)
url = "/" + "1" * 60
rp.can_fetch(url, "mybot")  # freezes

Database specific

{
    "cwe_ids": [
        "CWE-1333",
        "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T18:43:02Z",
    "nvd_published_at": null,
    "severity": "HIGH"
}

References

Affected packages

PyPI / protego

Package

Name: protego; View open source insights on deps.dev
Purl: pkg:pypi/protego

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

0.6.2

Affected versions

0.*

0.1.dev0

0.1

0.1.12

0.1.14

0.1.15

0.1.16

0.2.0

0.2.1

0.3.0

0.3.1

0.4.0

0.5.0

0.6.0

0.6.1

Database specific

last_known_affected_version_range

"<= 0.6.1"

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-wjmf-p669-5m5p/GHSA-wjmf-p669-5m5p.json"