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CVE-2019-16201

27
FAUCET Score

CVE-2019-16201 is a regular expression Denial of Service (DoS) vulnerability affecting WEBrick::HTTPAuth::DigestAuth in Ruby versions through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4, as well as Debian Linux distributions utilizing these Ruby versions. This flaw, rated with a CVSS score of 7.5 (High), allows an unauthenticated attacker to cause a denial of service by sending specially crafted requests to an exposed WEBrick server using DigestAuth. There is currently no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
>= 2.4.0, <= 2.4.7CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
>= 2.5.0, <= 2.5.6CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
>= 2.6.0, <= 2.6.4CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.13%
Probability of exploitation in next 30 days
EPSS Percentile
91.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0513 is in the 85th percentile among its peer group of 51,553 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (16)

microsoftpatch availablevia msrc
Product: 17016-16820Fixed in: 2.6.7-1
microsoftpatch availablevia msrc
Product: cm1 ruby 2.6.7-1 on CBL Mariner 1.0Fixed in: 2.6.7-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 2.6.7-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 2.6.7-1
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.2 Extended Update SupportFixed in: ruby:2.6-8020020220201131207.4cda2c84
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-ruby25-ruby-0:2.5.9-9.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-ruby26-ruby-0:2.6.7-119.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSFixed in: rh-ruby25-ruby-0:2.5.9-9.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-ruby25-ruby-0:2.5.9-9.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSFixed in: rh-ruby26-ruby-0:2.6.7-119.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: ruby:2.5-8040020200923213910.522a0ee4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: ruby:2.6-8040020210430142949.522a0ee4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Update Services for SAP SolutionsFixed in: ruby:2.6-8010020220201152941.c27ad7f8
View patch
redhatend of lifevia redhat_api
Product: Red Hat 3scale API Management Platform 2Fixed in: 3amp-system
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: ruby
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-ruby24-ruby

Vendor Advisories (3)

microsoft2020-Sep/CVE-2019-16201

CVE-2019-16201

Sep 8, 2020
microsoft2019-Nov/CVE-2019-16201Important

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.

Nov 12, 2019
redhatCVE-2019-16201Moderate

ruby: Regular expression denial of service vulnerability of WEBrick's Digest authentication

Oct 1, 2019

References

lists.opensuse.org / opensuse-security-announce/2020-03/msg00041.html
hackerone.com / reports/661722
Third Party Advisory
lists.debian.org / debian-lts-announce/2019/11/msg00025.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2019/12/msg00009.html
lists.debian.org / debian-lts-announce/2020/08/msg00027.html
lists.debian.org / debian-lts-announce/2023/04/msg00033.html
seclists.org / bugtraq/2019/Dec/31
seclists.org / bugtraq/2019/Dec/32
security.gentoo.org / glsa/202003-06
debian.org / security/2019/dsa-4587
oracle.com / security-alerts/cpujan2020.html