Denial of Service in uap-core when processing crafted User-Agent strings
Impact
Some regexes are vulnerable to regular expression denial of service (REDoS) due to overlapping capture groups. This allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to maliciously crafted long strings.
Patches
Please update uap-core to >= v0.7.3
Downstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.
Details
Each vulnerable regular expression reported here contains 3 overlapping capture groups. Backtracking has approximately cubic time complexity with respect to the length of the user-agent string.
Regex 1:
\bSmartWatch *\( *([^;]+) *; *([^;]+) *;is vulnerable in portion *([^;]+) * and can be attacked with
"SmartWatch(" + (" " * 3500) + "z"e.g.
SmartWatch( zRegex 2:
; *([^;/]+) Build[/ ]Huawei(MT1-U06|[A-Z]+\d+[^\);]+)[^\);]*\)is vulnerable in portion \d+[^\);]+[^\);]* and can be attacked with
";A Build HuaweiA" + ("4" * 3500) + "z"Regex 3:
(HbbTV)/[0-9]+\.[0-9]+\.[0-9]+ \([^;]*; *(LG)E *; *([^;]*) *;[^;]*;[^;]*;\)is vulnerable in portion *([^;]*) * and can be attacked with
"HbbTV/0.0.0 (;LGE;" + (" " * 3500) + "z"Regex 4:
(HbbTV)/[0-9]+\.[0-9]+\.[0-9]+ \([^;]*; *(?:CUS:([^;]*)|([^;]+)) *; *([^;]*) *;.*;is vulnerable in portions *(?:CUS:([^;]*)|([^;]+)) * and *([^;]*) * and can be attacked with
"HbbTV/0.0.0 (;CUS:;" + (" " * 3500) + "z"
"HbbTV/0.0.0 (;" + (" " * 3500) + "z"
"HbbTV/0.0.0 (;z;" + (" " * 3500) + "z"Reported by Ben Caller @bcaller
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | uap-core | < 0.7.3 | 0.7.3 |
References
- https://github.com/ua-parser/uap-core/security/advisories/GHSA-cmcx-xhr8-3w9p
- https://github.com/ua-parser/uap-ruby/security/advisories/GHSA-pcqq-5962-hvcw
- https://nvd.nist.gov/vuln/detail/CVE-2020-5243
- https://github.com/ua-parser/uap-core/commit/0afd61ed85396a3b5316f18bfd1edfaadf8e88e1
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/user_agent_parser/CVE-2020-5243.yml
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1333, CWE-20- Platform
- npm
- Package
uap-core- Disclosed
- 20.02.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-cmcx-xhr8-3w9p - CC BY 4.0
Vulnerability history: uap-core
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 03.2019 02.2021
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 2
Disclosures per year
- 2019: 1
- 2020: 1
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
-
Denial of Service in uap-core when processing crafted User-Agent strings this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.