UBUNTU-CVE-2026-85999

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Source
https://ubuntu.com/security/CVE-2026-85999
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85999.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-85999
Upstream
Published
2026-09-17T16:18:00Z
Modified
2026-09-23T23:36:45Z
Severity
  • 5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L CVSS Calculator
  • Ubuntu - medium
Summary
[none]
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.

References

Affected packages

Ubuntu:20.04:LTS / soupsieve

Package

Name
soupsieve
Purl
pkg:deb/ubuntu/soupsieve?arch=source&distro=focal

Affected ranges

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

Affected versions

1.*
1.9.2+dfsg-2ubuntu1
1.9.4+dfsg-1
1.9.5+dfsg-1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "python-soupsieve",
            "binary_version":  "1.9.5+dfsg-1"
        },
        {
            "binary_name":  "python3-soupsieve",
            "binary_version":  "1.9.5+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85999.json"

Ubuntu:22.04:LTS / soupsieve

Package

Name
soupsieve
Purl
pkg:deb/ubuntu/soupsieve?arch=source&distro=jammy

Affected ranges

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

Affected versions

2.*
2.2.1-2
2.3-1
2.3.1-1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "python3-soupsieve",
            "binary_version":  "2.3.1-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85999.json"

Ubuntu:24.04:LTS / soupsieve

Package

Name
soupsieve
Purl
pkg:deb/ubuntu/soupsieve?arch=source&distro=noble

Affected ranges

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

Affected versions

2.*
2.4.1-2
2.5-1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "python3-soupsieve",
            "binary_version":  "2.5-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85999.json"

Ubuntu:26.04:LTS / soupsieve

Package

Name
soupsieve
Purl
pkg:deb/ubuntu/soupsieve?arch=source&distro=resolute

Affected ranges

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

Affected versions

2.*
2.7-2
2.8.1-1
2.8.3-1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "python3-soupsieve",
            "binary_version":  "2.8.3-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-85999.json"