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Fencer Vulns
medium 5.3

CVE-2019-16254 json

Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 allows HTTP Response Splitting.

published 2019-11-26 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-7060

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.6%
EPSS 4.6% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

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.

Patch / fix

  • jruby Debian 14, Debian 13, Debian 12 9.3.9.0+ds-1

debian advisories DEBIAN-CVE-2019-16254

  • ruby2.3 Ubuntu 16.04 LTS 2.3.1-2~ubuntu16.04.14
  • ruby2.5 Ubuntu 18.04 LTS 2.5.1-1ubuntu1.6
  • jruby Ubuntu Pro 14.04 LTS 1.5.6-9+deb8u2build0.14.04.1~esm2

ubuntu advisories UBUNTU-CVE-2019-16254

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ruby4.0 hummingbird 1 4.0.0-33.3.hum1
  • ruby4.0-libs hummingbird 1 4.0.0-33.3.hum1
  • ruby4.0-bundled-gems hummingbird 1 4.0.0-33.3.hum1
  • ruby4.0-default-gems hummingbird 1 4.0.0-33.3.hum1
  • ruby3.3 hummingbird 1 3.3.10-23.1.hum1
  • ruby3.3-libs hummingbird 1 3.3.10-23.1.hum1
  • ruby3.3-bundled-gems hummingbird 1 3.3.10-23.1.hum1
  • ruby3.3-default-gems hummingbird 1 3.3.10-23.1.hum1

red hat advisories RHSA-2026:8838RHSA-2026:7305RHSA-2026:7307RHSA-2022:0582RHSA-2022:0581RHSA-2021:2588

  • ruby2.1 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 2.1.9-19.3.2
  • yast2-ruby-bindings SLES for SAP 12 SP2, SLES 12 SP2-LTSS, SLES 12 SP2-BCL +1 more 3.1.53-9.8.1
  • ruby2.5 SLES for SAP 15, SLES 15-LTSS, SLE Module for Basesystem 15 SP1 +2 more 2.5.7-4.8.1

suse advisories SUSE-SU-2020:1570-1SUSE-SU-2020:0737-1

  • ruby2.5 openSUSE Leap 15.1 2.5.7-lp151.4.6.1

opensuse advisories openSUSE-SU-2020:0395-1

  • rubygem-pg AlmaLinux 8 1.1.4-1.module_el8.5.0+250+ba22dbf7
  • rubygem-pg AlmaLinux 8 1.1.4-1.module_el8.5.0+2623+08a8ba32
  • rubygem-abrt AlmaLinux 8 0.3.0-4.module_el8.5.0+259+8cec6917
  • rubygem-abrt AlmaLinux 8 0.3.0-4.module_el8.5.0+2623+08a8ba32
  • rubygem-bson AlmaLinux 8 4.5.0-1.module_el8.5.0+2623+08a8ba32
  • rubygem-bson AlmaLinux 8 4.5.0-1.module_el8.5.0+250+ba22dbf7
  • rubygem-mongo AlmaLinux 8 2.8.0-1.module_el8.5.0+250+ba22dbf7
  • rubygem-mongo AlmaLinux 8 2.8.0-1.module_el8.5.0+2623+08a8ba32

almalinux advisories ALSA-2021:2588ALSA-2021:2587

  • ruby Rocky Linux 8 2.6.7-107.module+el8.4.0+593+8d7f9f0c
  • rubygem-pg Rocky Linux 8 1.1.4-1.module+el8.5.0+738+032c9c02
  • rubygem-pg Rocky Linux 8 1.1.4-1.module+el8.4.0+446+80b53620
  • rubygem-pg Rocky Linux 8 1.1.4-1.module+el8.4.0+593+8d7f9f0c
  • rubygem-abrt Rocky Linux 8 0.3.0-4.module+el8.5.0+738+032c9c02
  • rubygem-abrt Rocky Linux 8 0.3.0-4.module+el8.3.0+167+5c390590
  • rubygem-abrt Rocky Linux 8 0.3.0-4.module+el8.4.0+592+03ff458a
  • rubygem-bson Rocky Linux 8 4.5.0-1.module+el8.4.0+593+8d7f9f0c

rocky linux advisories RLSA-2021:2588RLSA-2021:2587

  • ruby Alpine 3.10, Alpine 3.9, Alpine 3.8 2.5.7-r0
  • ruby Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 2.6.5-r0
  • ruby Alpine 3.7 2.4.10-r0

alpine advisories ALPINE-CVE-2019-16254

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ruby Arch Linux 2.6.5-1

arch linux advisories AVG-1039

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-16254 updated cvss 5.3

ruby: HTTP response splitting in WEBrick

  • Red Hat 3scale API Management Platform 2 3amp-system 3amp-system
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 5 ruby Red Hat Enterprise Linux 6 ruby, ruby-ri, ruby-irb, ruby-libs, ruby-rdoc, ruby-tcltk
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 ruby, ruby-irb, rubygems, ruby-libs, ruby-tcltk, rubygem-json, +6 more Red Hat Software Collections rh-ruby24-ruby, rh-ruby24-ruby-irb, rh-ruby24-rubygems, rh-ruby24-ruby-libs, rh-ruby24-rubygem-json, rh-ruby24-rubygem-rake, +11 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux AppStream (v. 8) ruby 2.5.9-107.module+el8.4.0+10822+fe4fffb1, ruby 2.6.7-107.module+el8.4.0+10830+bbd85cce, rubygem-pg 1.0.0-2.module+el8.1.0+3656+f80bfa1d, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-irb 2.5.9-107.module+el8.4.0+10822+fe4fffb1, ruby-libs 2.5.9-107.module+el8.4.0+10822+fe4fffb1, +40 more
    fixed: vendor fix RHSA-2021:2587
  • Red Hat Enterprise Linux AppStream E4S (v. 8.1) ruby 2.6.9-107.module+el8.1.0+14088+04cf326e, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-libs 2.6.9-107.module+el8.1.0+14088+04cf326e, rubygem-abrt 0.3.0-4.module+el8.1.0+3653+beb38eb0, rubygem-bson 4.5.0-1.module+el8.1.0+3653+beb38eb0, rubygem-mongo 2.8.0-1.module+el8.1.0+3653+beb38eb0, +17 more
    fixed: vendor fix RHSA-2022:0581
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) ruby 2.6.9-107.module+el8.2.0+14086+86d863af, rubygem-pg 1.1.4-1.module+el8.1.0+3653+beb38eb0, ruby-libs 2.6.9-107.module+el8.2.0+14086+86d863af, rubygem-abrt 0.3.0-4.module+el8.1.0+3653+beb38eb0, rubygem-bson 4.5.0-1.module+el8.1.0+3653+beb38eb0, rubygem-mongo 2.8.0-1.module+el8.1.0+3653+beb38eb0, +17 more
    fixed: vendor fix RHSA-2022:0582
  • Red Hat Hardened Images ruby3.4 3.4.8-31.1.hum1, ruby4.0 4.0.0-33.3.hum1, ruby3.3 3.3.10-23.1.hum1, ruby3.4-libs 3.4.8-31.1.hum1, ruby4.0-libs 4.0.0-33.3.hum1, ruby3.3-libs 3.3.10-23.1.hum1, +6 more
    fixed: vendor fix RHSA-2026:7305
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby26-ruby 2.6.7-119.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby26-ruby-libs 2.6.7-119.el7, +29 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby25-rubygem-json 2.1.0-9.el7, rh-ruby25-rubygem-psych 3.0.2-9.el7, +11 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby26-ruby 2.6.7-119.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby26-ruby-libs 2.6.7-119.el7, +29 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-ruby25-ruby 2.5.9-9.el7, rh-ruby26-ruby 2.6.7-119.el7, rh-ruby25-ruby-irb 2.5.9-9.el7, rh-ruby25-ruby-libs 2.5.9-9.el7, rh-ruby25-rubygems 2.7.6.3-9.el7, rh-ruby26-ruby-libs 2.6.7-119.el7, +29 more
    fixed: vendor fix RHSA-2021:2104
show 1 more
  • Red Hat Hardened Images rubygem3.3-rbs 3.4.0-23.1.hum1, rubygem3.3-rss 0.3.1-23.1.hum1, rubygem3.4-rbs 3.8.0-31.1.hum1, rubygem3.4-rss 0.3.1-31.1.hum1, rubygem4.0-rss 0.3.2-33.3.hum1, rubygem3.3-irb 1.13.1-23.1.hum1, +45 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

4.57% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.