How severe is CVE-2018-20164?

CVE-2018-20164 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2018-20164 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-20164?

CVE-2018-20164 affects Uaparser User Agent Parser-core. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-20164?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-20164 published?

CVE-2018-20164 was published on 2019-02-13 and last updated on 2026-06-17.

CVE-2018-20164

CVE-2018-20164 is a medium-severity vulnerability in Uaparser User Agent Parser-core with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-185.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-185
Affected product: Uaparser User Agent Parser-core
Published: 2019-02-13
Last modified: 2026-06-17

Description

An issue was discovered in regex.yaml (aka regexes.yaml) in UA-Parser UAP-Core before 0.6.0. A Regular Expression Denial of Service (ReDoS) issue allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to a value containing a long digit string. (The UAP-Core project contains the vulnerability, propagating to all implementations.)

Frequently asked questions

What is CVE-2018-20164?: An issue was discovered in regex.yaml (aka regexes.yaml) in UA-Parser UAP-Core before 0.6.0. A Regular Expression Denial of Service (ReDoS) issue allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to a value containing a long digit string. (The UAP-Core project contains the vulnerability, propagating to all implementations.)
How severe is CVE-2018-20164?: CVE-2018-20164 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2018-20164 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-20164?: CVE-2018-20164 affects Uaparser User Agent Parser-core. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-20164?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-20164 published?: CVE-2018-20164 was published on 2019-02-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:uaparser:user_agent_parser-core:*:*:*:*:*:*:*:*

Other CWE-185 vulnerabilities

CVE-2024-52289 — Critical (CVSS 9.8): authentik is an open-source identity provider. Redirect URIs in the OAuth2 provider in authentik are checked by RegEx…
CVE-2019-12798 — Critical (CVSS 9.8): An issue was discovered in Artifex MuJS 1.0.5. regcompx in regexp.c does not restrict regular expression program size,…
CVE-2026-25896 — Critical (CVSS 9.3): fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based…
CVE-2026-4296 — High (CVSS 8.8): An incorrect regular expression vulnerability was identified in GitHub Enterprise Server that allowed an attacker to…
CVE-2018-17984 — High (CVSS 7.8): An unanchored /[a-z]{2}/ regular expression in ISPConfig before 3.1.13 makes it possible to include arbitrary files,…
CVE-2026-33418 — High (CVSS 7.5): DiceBear is an avatar library for designers and developers. Prior to version 9.4.2, the `ensureSize()` function in…

Browse all CWE-185 vulnerabilities →