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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-25126 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Detection & 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-25126 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-25126. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
| 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?
O3 Security finds CVE-2024-25126 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.