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CVE-2018-20164

19
FAUCET Score

CVE-2018-20164 describes a Regular Expression Denial of Service (ReDoS) vulnerability in UA-Parser UAP-Core versions prior to 0.6.0, specifically within its regex.yaml file. This flaw allows remote attackers to overload a server by sending HTTP(S) requests with a crafted User-Agent header containing a long string of digits. The vulnerability has a CVSS score of 5.3 (Medium), indicating a low attack complexity and no user interaction required, with the primary impact being a denial of service (availability). While the EPSS score is low, suggesting a low probability of exploitation, it is important to note the potential for service disruption. Currently, there is no evidence of active exploitation, nor are there publicly available exploit modules in Metasploit or Nuclei. The vulnerability has received minimal community discussion and media coverage, suggesting it is not a widely publicized or actively targeted threat.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.6.0CPE matchmatch criteria
cpe:2.3:a:uaparser:user_agent_parser-core:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.3MEDIUM

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.30%
Probability of exploitation in next 30 days
EPSS Percentile
87.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0330 is in the 82nd percentile among its peer group of 23,701 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: uap-coreFixed in: 0.6.0

Vendor Advisories (1)

npmGHSA-fx7m-j728-mjw3medium

uap-core Regular Expression Denial of Service issue

Mar 6, 2019

References

github.com / ua-parser/uap-core/commit/010ccdc7303546cd22b9da687c29f4a996990014
PatchThird Party Advisory
github.com / ua-parser/uap-core/commit/156f7e12b215bddbaf3df4514c399d683e6cdadc
PatchThird Party Advisory
github.com / ua-parser/uap-core/issues/332
x41-dsec.de / lab/advisories/x41-2018-009-uaparser
ExploitThird Party Advisory