CVE-2019-16254

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-11-26 · updated 2026-06-17
Weakness: CWE-74

Description

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.

Affected products

Debian Linux: 8.0
Ruby: through 2.3.0; from 2.4.0 through 2.4.7; from 2.5.0 through 2.5.6; from 2.6.0 through 2.6.4

References

http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00041.html
https://hackerone.com/reports/331984
https://lists.debian.org/debian-lts-announce/2019/11/msg00025.html
https://lists.debian.org/debian-lts-announce/2019/12/msg00009.html
https://lists.debian.org/debian-lts-announce/2020/08/msg00027.html
https://lists.debian.org/debian-lts-announce/2023/04/msg00033.html
https://seclists.org/bugtraq/2019/Dec/31
https://seclists.org/bugtraq/2019/Dec/32
https://security.gentoo.org/glsa/202003-06
https://www.debian.org/security/2019/dsa-4586
https://www.debian.org/security/2019/dsa-4587
https://www.oracle.com/security-alerts/cpujan2020.html

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