CVE-2020-5243: uap-core before 0.7.3 is vulnerable to a denial of service attack when processing crafted User-Agent strings

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MEDIUM 5.7UPGRADE

CVE-2020-5243 is a medium-severity flaw (CVSS 5.7) affecting uap-core. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.7 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-20, CWE-1333
Published	2020-02-21
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: uap-core project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-02-21 00:15 UTCPublished CVE record published
2026-06-17 03:21 UTCUpdated Record last modified

uap-core project uap-core UPGRADE

Affected: < 0.7.3

Fixed in: 0.7.3

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls uap-core

2. UPGRADE to 0.7.3

npm install uap-core@">=0.7.3"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-5243?

uap-core: upgrade to 0.7.3. Exact commands for each OS are on this page.

Is CVE-2020-5243 being exploited?

CVE-2020-5243 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-5243 affect?

CVE-2020-5243 affects uap-core. Severity is medium (CVSS 5.7). 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

How urgent is CVE-2020-5243?

Priority 46/100. Public exploit reference

Related CVEs

CVE-2021-21317 MEDIUM 5.3 UPGRADE uap-core in an open-source npm package which contains the core of BrowserScope's original user agent string pa

References

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