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CVE-2023-27530: A DoS vulnerability exists in Rack <v3.0.4.2, <v2.2.6.3, <v2.1.4.3 and <v2.0.9.3 within in the Multipart MIME

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HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2023-27530 is a high-severity flaw (CVSS 7.5) affecting rack, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A DoS vulnerability exists in Rack <v3.0.4.2, <v2.2.6.3, <v2.1.4.3 and <v2.0.9.3 within in the Multipart MIME parsing code in which could allow an attacker to craft requests that can be abuse to cause multipart parsing to take longer than expected.

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance1.8% (top 21%)
CISA exploited listNo
WeaknessCWE-400, CWE-770
Published2023-03-10
Last modified2026-10-24
Publisher (CNA): HackerOne · Vendor: debian · rack

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Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

rack rack UPGRADE
Affected: < 2.0.9.3 · >= 2.1.0 and < 2.1.4.3 · >= 2.2.0 and < 2.2.6.3 · >= 3.0.0 and < 3.0.4.2
Fixed in: 2.0.9.3, 2.1.4.3, 2.2.6.3, 3.0.4.2
Safe to downgrade to: a release before 2.1.0
1. Check installed version
apt-cache policy rack || rpm -q rack || rack --version
2. UPGRADE to 2.0.9.3 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade rack
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade rack
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 2.1.0 (Debian / Ubuntu)
apt-cache madison rack sudo apt install rack=<VERSION_BEFORE_2.1.0> sudo apt-mark hold rack
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list rack sudo dnf downgrade rack-<VERSION_BEFORE_2.1.0> sudo dnf versionlock add rack
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
debian debian linux MITIGATE
Affected: 10.0 · 11.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 10.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
RubyGems · rack · FIXED · 2.0.9.3 · vulnerable: < 2.0.9.3 · source
bundle update rack bundle list | grep rack
Fedora 46 · gnome-shell-extension-tiling-assistant · FIXED · 56-1.fc46 · FEDORA-2026-ebf66a5321 · source
sudo dnf upgrade --advisory=FEDORA-2026-ebf66a5321
Ubuntu 20.04 · ruby-rack · FIXED · 2.0.7-2ubuntu0.1+esm4
sudo apt update && sudo apt install --only-upgrade ruby-rack dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-rack)" ge "2.0.7-2ubuntu0.1+esm4" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 24.04 · ruby-rack · NOT AFFECTED
Ubuntu 22.04 · ruby-rack · FIXED · 2.1.4-5ubuntu1.1
sudo apt update && sudo apt install --only-upgrade ruby-rack dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-rack)" ge "2.1.4-5ubuntu1.1" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 24.10 · ruby-rack · NOT AFFECTED
Ubuntu 25.04 · ruby-rack · NOT AFFECTED
Debian 12 · ruby-rack · FIXED · 2.2.6.4-1
sudo apt update && sudo apt install --only-upgrade ruby-rack dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-rack)" ge "2.2.6.4-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · ruby-rack · FIXED · 2.2.6.4-1
sudo apt update && sudo apt install --only-upgrade ruby-rack dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-rack)" ge "2.2.6.4-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 8 · pcs · FIXED · pcs-0.10.15-4.el8_8.1
sudo dnf upgrade --advisory=RHSA-2023:3082 rpm -q pcs
RHEL 8.4 Extended Update Support · pcs · FIXED · pcs-0.10.8-1.el8_4.4
sudo dnf upgrade --advisory=RHSA-2023:1961 rpm -q pcs
RHEL 8.6 Extended Update Support · pcs · FIXED · pcs-0.10.12-6.el8_6.4
sudo dnf upgrade --advisory=RHSA-2023:3403 rpm -q pcs
RHEL 9 · pcs · FIXED · pcs-0.11.4-7.el9_2
sudo dnf upgrade --advisory=RHSA-2023:2652 rpm -q pcs
RHEL 9.0 Extended Update Support · pcs · FIXED · pcs-0.11.1-10.el9_0.4
sudo dnf upgrade --advisory=RHSA-2023:1981 rpm -q pcs
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-27530?

rack: upgrade to 2.0.9.3, 2.1.4.3, 2.2.6.3, 3.0.4.2; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-27530 being exploited?

CVE-2023-27530 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-27530 affect?

CVE-2023-27530 affects rack, debian linux. Severity is high (CVSS 7.5). A DoS vulnerability exists in Rack <v3.0.4.2, <v2.2.6.3, <v2.1.4.3 and <v2.0.9.3 within in the Multipart MIME parsing code in which could allow an attacker to craft requests that can be abuse to cause multipart parsing to take longer than e

How urgent is CVE-2023-27530?

Priority 56/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

References

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