What’s Vulnerable › Vulnerabilities

CVE-2020-5243: Denial of Service in uap-core when processing crafted User-Agent strings

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-02-21 · updated 2026-06-17
• Weakness: CWE-20

Description

uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings. 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. This has been patched in uap-core 0.7.3.

Affected products

• ua-parser uap-core: before 0.7.3 — fixed in 0.7.3

How to fix

Upgrade to a fixed version: ua-parser uap-core 0.7.3. Check the vendor advisory for mitigations.

References

• https://github.com/ua-parser/uap-core/commit/0afd61ed85396a3b5316f18bfd1edfaadf8e88e1
• https://github.com/ua-parser/uap-core/security/advisories/GHSA-cmcx-xhr8-3w9p
• https://github.com/ua-parser/uap-core/commit/0afd61ed85396a3b5316f18bfd1edfaadf8e88e1
• https://github.com/ua-parser/uap-core/security/advisories/GHSA-cmcx-xhr8-3w9p

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