How severe is CVE-2024-26142?

CVE-2024-26142 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2024-26142?

CVE-2024-26142 affects the following packages: actionpack (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2024-26142?

Update actionpack to 7.1.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-26142 is resolved across your whole dependency graph.

How do I detect CVE-2024-26142 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for actionpack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2024-26142 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2024-26142 actively exploited in the wild?

No public exploit code has been indexed for CVE-2024-26142 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2024-26142?

CVE-2024-26142 has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 74th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2024-26142?

CVE-2024-26142 is classified as CWE-1333 (CWE-1333). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2024-26142 published, and has it been updated?

CVE-2024-26142 was published on February 27, 2024 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

HIGH severity

CVE-2024-26142 — actionpack

HIGHFix: rails/rails@b4d3bfb

CVE-2024-26142 is a high-severity (CVSS 7.5) CWE-1333 vulnerability in actionpack. A fix is available for actionpack — see the affected versions and patch details below.

Rails possible ReDoS vulnerability in Accept header parsing in Action Dispatch

Also known asBIT-rails-2024-26142GHSA-jjhx-jhvp-74wq

Published

Feb 27, 2024

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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.

Exploitation and automatability from CISA’s SSVC triage for CVE-2024-26142.

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs74th percentile — riskier than 74% of all scored CVEsHighest risk

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

1 pkg affected

💎actionpack

Real-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

Possible ReDoS vulnerability in Accept header parsing in Action Dispatch

There is a possible ReDoS vulnerability in the Accept header parsing routines of Action Dispatch. This vulnerability has been assigned the CVE identifier CVE-2024-26142.

Versions Affected: >= 7.1.0, < 7.1.3.1 Not affected: < 7.1.0 Fixed Versions: 7.1.3.1

Impact

Carefully crafted Accept headers can cause Accept header parsing in Action Dispatch to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade or use one of the workarounds immediately.

Ruby 3.2 has mitigations for this problem, so Rails applications using Ruby 3.2 or newer are unaffected.

Releases

The fixed releases are available at the normal locations.

Workarounds

There are no feasible workarounds for this issue.

Patches

To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.

7-1-accept-redox.patch - Patch for 7.1 series

Credits

Thanks svalkanov for the report and patch!

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`actionpack`	≥ 7.1.0&&< 7.1.3.1	7.1.3.1`bundle update actionpack --conservative`

Affected Products

1 product · 1 configurations

Application

railsrubyonrails

≥ 7.1.0 && < 7.1.3.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for actionpack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update actionpack to 7.1.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-26142 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

# Possible ReDoS vulnerability in Accept header parsing in Action Dispatch There is a possible ReDoS vulnerability in the Accept header parsing routines of Action Dispatch. This vulnerability has been assigned the CVE identifier CVE-2024-26142. Versions Affected: >= 7.1.0, < 7.1.3.1 Not affected: < 7.1.0 Fixed Versions: 7.1.3.1 Impact ------ Carefully crafted Accept headers can cause Accept header parsing in Action Dispatch to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade or use one of th