CVE-2019-16201

WEBrick::HTTPAuth::DigestAuth in Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 has a regular expression Denial of Service cause by looping/backtracking. A victim must expose a WEBrick server that uses DigestAuth to the Internet or a untrusted network.

Published: 2019-11-26 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-16201 is rated High Risk (66.3/100): CVSS High severity, with high exploitation likelihood (EPSS 4.99%, 91th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +4.38% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2019-16201

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.60% 4.99% +4.38%
2 2025-12-28 0.47% 0.60% +0.13%
3 2025-12-27 — 0.47% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-16201

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.8 2.0 HIGH
AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 6.9 [email protected]

Weakness enumeration for CVE-2019-16201

OS Trackers for CVE-2019-16201

vendor priority summary link
alpine high CVE-2019-16201: 1 source package rows (ruby); 30 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 20. https://security.alpinelinux.org/vuln/CVE-2019-16201
debian not yet assigned CVE-2019-16201 not yet assigned priority: Debian including 1 source packages (jruby), 4 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2019-16201
gentoo normal CVE-2019-16201: 1 GLSA(s) (202003-06), 1 atom(s) (dev-lang/ruby); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2019-16201
redhat medium — https://access.redhat.com/security/cve/CVE-2019-16201
suse medium CVE-2019-16201 severity moderate: SUSE including 311 source package names (2.17-17.3:libruby2_5-2_5-2.5.7-4.8.1, 2.17-17.3:ruby2.5-2.5.7-4.8.1, …), 1053 product×package rows across 270 product lines (Container bci/ruby, Container suse/rmt-server, … (270 product lines)): Fixed 860, Known Affected 157, Known Not Affected 30, Will Not Fix 6. https://www.suse.com/security/cve/CVE-2019-16201/
ubuntu medium CVE-2019-16201 medium priority: Ubuntu including 3 source packages (jruby, ruby2.3, ruby2.5), 52 status rows across 18 suites (bionic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 30, ignored 9, released 6, needs-triage 4, needed 3. https://ubuntu.com/security/CVE-2019-16201

Affected software / configurations for CVE-2019-16201

Vendor Product Version Raw CPE
ruby-lang ruby >= 2.4.0, <= 2.4.7 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
ruby-lang ruby >= 2.5.0, <= 2.5.6 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
ruby-lang ruby >= 2.6.0, <= 2.6.4 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

References for CVE-2019-16201

cvelogic Threat Intelligence