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Fencer Vulns
medium 5.3

CVE-2023-27539 json

Possible Denial of Service Vulnerability in Rack's header parsing

published 2023-03-15 3 y ago modified 2026-06-17 4 mo ago also GHSA-c6qg-cjj8-47qp , EUVD-2023-0979

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits
0
none known

Summary

There is a denial of service vulnerability in the header parsing component of Rack.

Patch / fix

  • rubygems rack 2.2.6.4, 3.0.6.1
  • rack rack 2.2.6.4, 3.0.6.1
  • ruby-rack Debian 14, Debian 13, Debian 12 2.2.6.4-1

debian advisories DEBIAN-CVE-2023-27539

  • ruby-rack Ubuntu 22.04 LTS 2.1.4-5ubuntu1.1
  • ruby-rack Ubuntu Pro 14.04 LTS 1.5.2-3+deb8u3ubuntu1~esm7
  • ruby-rack Ubuntu Pro 16.04 LTS 1.6.4-3ubuntu0.2+esm5
  • ruby-rack Ubuntu Pro 18.04 LTS 1.6.4-4ubuntu0.2+esm5
  • ruby-rack Ubuntu Pro 20.04 LTS 2.0.7-2ubuntu0.1+esm4
  • ruby-rack Ubuntu Pro 22.04 LTS 2.1.4-5ubuntu1+esm4

ubuntu advisories UBUNTU-CVE-2023-27539

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

  • foreman satellite utils 6.14, satellite capsule 6.14, satellite 6.14 3.7.0.9-1.el8sat
  • foreman-cli satellite utils 6.14, satellite 6.14 3.7.0.9-1.el8sat
  • foreman-ec2 satellite 6.14 3.7.0.9-1.el8sat
  • rubygem-git satellite 6.14 1.18.0-1.el8sat
  • puppet-agent satellite capsule 6.14, satellite 6.14 7.26.0-3.el8sat
  • puppetserver satellite capsule 6.14, satellite 6.14 7.11.0-1.el8sat
  • rubygem-rack satellite capsule 6.14, satellite 6.14 2.2.7-1.el8sat
  • foreman-ovirt satellite 6.14 3.7.0.9-1.el8sat

red hat advisories RHSA-2023:6818RHSA-2023:3403RHSA-2023:3082RHSA-2023:2652RHSA-2023:1981RHSA-2023:1961

  • rubygem-rack OpenStack Cloud Crowbar 9, OpenStack Cloud Crowbar 8 1.6.13-3.19.1
  • rubygem-rack SLE High Availability Extension 15 SP4, SLE High Availability Extension 15 SP3, SLE High Availability Extension 15 SP2 +2 more 2.0.8-150000.3.18.1

suse advisories SUSE-SU-2023:1869-1SUSE-SU-2023:1685-1

  • rubygem-rack openSUSE Tumbleweed 3.1.18-1.3
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.22-1.1
  • rubygem-rack openSUSE Tumbleweed 3.1.12-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.11-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.6.4-1.1
  • rubygem-rack openSUSE Tumbleweed 3.0.7-1.1
  • rubygem-rack openSUSE Tumbleweed 3.0.9.1-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.8.1-1.1

opensuse advisories openSUSE-SU-2026:10358-1openSUSE-SU-2026:10286-1openSUSE-SU-2025:14875-1openSUSE-SU-2025:14811-1openSUSE-SU-2024:12789-1openSUSE-SU-2024:12805-1

  • pcs AlmaLinux 8 0.10.15-4.el8_8.1.alma
  • pcs-snmp AlmaLinux 8 0.10.15-4.el8_8.1.alma
  • pcs AlmaLinux 9 0.11.4-7.el9_2
  • pcs-snmp AlmaLinux 9 0.11.4-7.el9_2

almalinux advisories ALSA-2023:3082ALSA-2023:2652

  • pcs Rocky Linux 9 0.11.4-7.el9_2
  • pcs Rocky Linux 8 0.10.15-4.el8_8.1

rocky linux advisories RLSA-2023:2652RLSA-2023:3082

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-2023-27539 updated cvss 5.3

rubygem-rack: denial of service in header parsing

  • Red Hat 3scale API Management Platform 2 3scale-amp2/zync-rhel8, 3scale-amp2/backend-rhel8
    affected: workaround, no fix available, no fix planned “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.”
  • Red Hat Storage 3 rubygem-rack
    affected: workaround, no fix planned “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.”
  • Red Hat Enterprise Linux High Availability EUS (v.8.6) pcs 0.10.12-6.el8_6.4, pcs-snmp 0.10.12-6.el8_6.4
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:3403
  • Red Hat Enterprise Linux High Availability EUS (v.9.0) pcs 0.11.1-10.el9_0.4, pcs-snmp 0.11.1-10.el9_0.4
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:1981
  • Red Hat Enterprise Linux HighAvailability (v. 8) pcs 0.10.15-4.el8_8.1, pcs-snmp 0.10.15-4.el8_8.1
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:3082
  • Red Hat Enterprise Linux HighAvailability (v. 9) pcs 0.11.4-7.el9_2, pcs-snmp 0.11.4-7.el9_2
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:2652
  • Red Hat Enterprise Linux HighAvailability EUS (v.8.4) pcs 0.10.8-1.el8_4.4, pcs-snmp 0.10.8-1.el8_4.4
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:1961
  • Red Hat Enterprise Linux Resilient Storage EUS (v.8.6) pcs 0.10.12-6.el8_6.4, pcs-snmp 0.10.12-6.el8_6.4
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:3403
show 8 more
  • Red Hat Enterprise Linux Resilient Storage EUS (v.9.0) pcs 0.11.1-10.el9_0.4, pcs-snmp 0.11.1-10.el9_0.4
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:1981
  • Red Hat Enterprise Linux ResilientStorage (v. 8) pcs 0.10.15-4.el8_8.1, pcs-snmp 0.10.15-4.el8_8.1
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:3082
  • Red Hat Enterprise Linux ResilientStorage (v. 9) pcs 0.11.4-7.el9_2, pcs-snmp 0.11.4-7.el9_2
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:2652
  • Red Hat Enterprise Linux ResilientStorage EUS (v.8.4) pcs 0.10.8-1.el8_4.4, pcs-snmp 0.10.8-1.el8_4.4
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:1961
  • Red Hat Satellite 6.14 for RHEL 8 rubygem-rack 2.2.7-1.el8sat
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:6818
  • Red Hat RHOL 5.6 for RHEL 8 openshift-logging/fluentd-rhel8 v1.14.6-113
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:1953
  • Red Hat RHOL 5.7 for RHEL 8 openshift-logging/fluentd-rhel8 v1.14.6-140
    fixed: vendor fix “Setting Regexp.timeout in Ruby 3.2 is a possible workaround.” RHSA-2023:3495
  • Red Hat Enterprise Linux 7 pcs, pcs-snmp, python-clufter Red Hat Satellite 6.14 for RHEL 8 cjson 1.7.14-5.el8sat, katello 4.9.0-1.el8sat, libsolv 0.7.22-4.el8pc, libcomps 0.1.18-4.el8pc, python-idna 3.3-2.el8pc, candlepin 4.3.1-1.el8sat, +668 more Red Hat RHOL 5.6 for RHEL 8 openshift-logging/vector-rhel8 v0.21.0-77, openshift-logging/kibana6-rhel8 v6.8.1-350, openshift-logging/logging-loki-rhel8 v2.7.4-6, openshift-logging/eventrouter-rhel8 v0.4.0-106, openshift-logging/loki-rhel8-operator v5.6.5-6, openshift-logging/opa-openshift-rhel8 v0.1.0-71, +11 more Red Hat RHOL 5.7 for RHEL 8 openshift-logging/vector-rhel8 v0.21.0-94, openshift-logging/kibana6-rhel8 v6.8.1-363, openshift-logging/eventrouter-rhel8 v0.4.0-141, openshift-logging/logging-loki-rhel8 v2.8.0-18, openshift-logging/loki-rhel8-operator v5.7.2-12, openshift-logging/opa-openshift-rhel8 v0.1.0-99, +11 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
21 mo ago

Exploit prediction

1.06% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
rubygems rack
>=2.0.0, <2.2.6.4
>=3.0.0, <3.0.6.1
2.2.6.4
3.0.6.1

Affected products

  • Rails Rack

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.