CVE-2024-25126 is a medium-severity (CVSS 5.3) CWE-1333 vulnerability in rack. EPSS puts its 30-day exploitation probability at 35.4% (98th percentile). A fix is available for rack — see the affected versions and patch details below.
Rack ReDos in content type parsing (2nd degree polynomial)
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-25126.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
rack💎rackReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Summary
module Rack
class MediaType
SPLIT_PATTERN = %r{\s*[;,]\s*}
The above regexp is subject to ReDos. 50K blank characters as a prefix to the header will take over 10s to split.
PoC
A simple HTTP request with lots of blank characters in the content-type header:
request["Content-Type"] = (" " * 50_000) + "a,"
Impact
It's a very easy to craft ReDoS. Like all ReDoS the impact is debatable.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rack | ≥ 3.0.0&&< 3.0.9.1 | 3.0.9.1bundle update rack --conservative |
| 💎RubyGems | rack | ≥ 0.4&&< 2.2.8.1 | 2.2.8.1bundle update rack --conservative |
Affected Products
debian linuxdebianrackrackDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rack to 3.0.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-25126 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
No mitigation is currently available for this vulnerability. The recommendation is to perform updates as soon as they are available.Source: Red Hat security advisory for CVE-2024-25126 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | pcs-0:0.10.18-2.el8_10 | RHSA-2024:2953 |
| Red Hat Enterprise Linux 8.2 Telecommunications Update Service | pcs-0:0.10.4-6.el8_2.5 | RHSA-2024:2007 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | pcs-0:0.10.8-1.el8_4.5 | RHSA-2024:2584 |
| Red Hat Enterprise Linux 8.6 Extended Update Support | pcs-0:0.10.12-6.el8_6.5 | RHSA-2024:3431 |
| Red Hat Enterprise Linux 8.8 Extended Update Support | pcs-0:0.10.15-4.el8_8.2 | RHSA-2024:2581 |
| Red Hat Enterprise Linux 9 | pcs-0:0.11.7-2.el9_4 | RHSA-2024:2113 |
| Red Hat Enterprise Linux 9.0 Extended Update Support | pcs-0:0.11.1-10.el9_0.5 | RHSA-2024:1841 |
| Red Hat Enterprise Linux 9.2 Extended Update Support | pcs-0:0.11.4-7.el9_2.1 | RHSA-2024:1846 |
Frequently Asked Questions
Is CVE-2024-25126 in your dependencies?
Find it across RubyGems, including transitive dependencies.