UBUNTU-CVE-2026-55520

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Source
https://ubuntu.com/security/CVE-2026-55520
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55520.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-55520
Upstream
Published
2026-08-28T20:18:00Z
Modified
2026-09-02T19:36:26Z
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
  • Ubuntu - medium
Summary
[none]
Details

Protego is a pure-Python robots.txt parser with support for modern conventions. Prior to 0.6.2, protego._urlpattern._URLPattern._prepare_pattern_for_regex translates every asterisk in an Allow or Disallow directive into a lazy regular-expression wildcard, so a directive containing many asterisks creates exponential backtracking. After protego.Protego.parse processes a crafted robots.txt file, protego.Protego.can_fetch can spend an attacker-controlled period matching a near-miss URL and deny service to the crawler. The vulnerable path is src/protego/_urlpattern.py in the _URLPattern match logic. This issue is fixed in version 0.6.2.

References

Affected packages

Ubuntu:20.04:LTS / python-protego

Package

Name
python-protego
Purl
pkg:deb/ubuntu/python-protego?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.1.16+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-protego",
            "binary_version": "0.1.16+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55520.json"

Ubuntu:22.04:LTS / python-protego

Package

Name
python-protego
Purl
pkg:deb/ubuntu/python-protego?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.1.16+dfsg-2
0.1.16+dfsg-3
0.2.1+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-protego",
            "binary_version": "0.2.1+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55520.json"

Ubuntu:24.04:LTS / python-protego

Package

Name
python-protego
Purl
pkg:deb/ubuntu/python-protego?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.2.1+dfsg-1
0.3.0+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-protego",
            "binary_version": "0.3.0+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55520.json"

Ubuntu:25.10 / python-protego

Package

Name
python-protego
Purl
pkg:deb/ubuntu/python-protego?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.4.0+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-protego",
            "binary_version": "0.4.0+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55520.json"

Ubuntu:26.04:LTS / python-protego

Package

Name
python-protego
Purl
pkg:deb/ubuntu/python-protego?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.4.0+dfsg-1
0.5.0+dfsg-1
0.6.0+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-protego",
            "binary_version": "0.6.0+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55520.json"