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CVE-2019-16254

22
FAUCET Score

CVE-2019-16254 is a medium-severity HTTP Response Splitting vulnerability affecting Ruby versions through 2.4.7, 2.5.6, and 2.6.4, specifically when using the WEBrick library. An attacker can inject newline characters into response headers, leading to malicious content injection and client deception. This vulnerability has a CVSS score of 5.3, indicating a low impact on integrity and no impact on confidentiality or availability, with no user interaction required. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.3.0CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
>= 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

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
4.57%
Probability of exploitation in next 30 days
EPSS Percentile
90.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0457 is in the 87th percentile among its peer group of 23,725 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 (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
redhatvendor investigatingvia redhat_api
Product: Red Hat 3scale API Management Platform 2Fixed in: 3amp-system
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: ruby
redhatvendor investigatingvia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-ruby24-ruby

Vendor Advisories (3)

microsoft2020-Sep/CVE-2019-16254

CVE-2019-16254

Sep 8, 2020
microsoft2019-Nov/CVE-2019-16254Moderate

Ruby through 2.4.7 2.5.x through 2.5.6 and 2.6.x through 2.6.4 allows HTTP Response Splitting. If a program using WEBrick inserts untrusted input into the response header an attacker can exploit it to insert a newline character to split a header and inject malicious content to deceive clients. NOTE: this issue exists because of an incomplete fix for CVE-2017-17742 which addressed the CRLF vector but did not address an isolated CR or an isolated LF.

Nov 12, 2019
redhatCVE-2019-16254Low

ruby: HTTP response splitting in WEBrick

Oct 25, 2019

References

lists.opensuse.org / opensuse-security-announce/2020-03/msg00041.html
hackerone.com / reports/331984
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-4586
debian.org / security/2019/dsa-4587
oracle.com / security-alerts/cpujan2020.html
ruby-lang.org / ja/news/2019/10/01/http-response-splitting-in-webrick-cve-2019-16254
Vendor Advisory
ruby-lang.org / ja/news/2019/10/01/ruby-2-4-8-released
Vendor Advisory
ruby-lang.org / ja/news/2019/10/01/ruby-2-5-7-released
Vendor Advisory
ruby-lang.org / ja/news/2019/10/01/ruby-2-6-5-released
Vendor Advisory