How severe is GHSA-pgm4-439c-5jp6?

No CVSS score has been assigned to GHSA-pgm4-439c-5jp6 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-pgm4-439c-5jp6?

GHSA-pgm4-439c-5jp6 affects the following packages: actionpack (RubyGems). Ecosystems affected: RubyGems.

How do I fix GHSA-pgm4-439c-5jp6?

Update actionpack to 8.1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pgm4-439c-5jp6 is resolved across your whole dependency graph.

How do I detect GHSA-pgm4-439c-5jp6 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 GHSA-pgm4-439c-5jp6 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is GHSA-pgm4-439c-5jp6 actively exploited in the wild?

No public exploit code has been indexed for GHSA-pgm4-439c-5jp6 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 GHSA-pgm4-439c-5jp6?

GHSA-pgm4-439c-5jp6 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 18th 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 GHSA-pgm4-439c-5jp6?

GHSA-pgm4-439c-5jp6 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-pgm4-439c-5jp6 published, and has it been updated?

GHSA-pgm4-439c-5jp6 was published on March 23, 2026 and was last updated on September 10, 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

Rails has a possible XSS vulnerability in its Action Pack debug exceptionsGHSA-pgm4-439c-5jp6

Fix: rails/rails@6752711

GHSA-pgm4-439c-5jp6 is a Cross-site Scripting (XSS) vulnerability in actionpack. A fix is available for actionpack — see the affected versions and patch details below.

Also known asCVE-2026-33167

Published

Mar 23, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-pgm4-439c-5jp6.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs18th percentile — riskier than 18% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

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

Impact

The debug exceptions page does not properly escape exception messages. A carefully crafted exception message could inject arbitrary HTML and JavaScript into the page, leading to XSS. This affects applications with detailed exception pages enabled (config.consider_all_requests_local = true), which is the default in development.

Releases

The fixed releases are available at the normal locations.

Credit

This issue was responsibly reported by Hackerone researcher fbettag.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`actionpack`	≥ 8.1.0&&< 8.1.2.1	8.1.2.1`bundle update actionpack --conservative`

Affected Products

1 product · 1 configurations

Application

railsrubyonrails

≥ 8.1.0 && < 8.1.2.1

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 8.1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pgm4-439c-5jp6 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

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.

Red HatModerate

Workaround published by Red Hat

To mitigate this issue, ensure that `config.consider_all_requests_local` is set to `false` in production environments for Rails applications. This configuration prevents the display of detailed exception pages, thereby eliminating the vector for this XSS vulnerability. This change may require a restart of the Rails application to take effect.

Source: Red Hat security advisory for GHSA-pgm4-439c-5jp6 (CC BY 4.0)

Frequently Asked Questions

### Impact The debug exceptions page does not properly escape exception messages. A carefully crafted exception message could inject arbitrary HTML and JavaScript into the page, leading to XSS. This affects applications with detailed exception pages enabled (`config.consider_all_requests_local = true`), which is the default in development. ### Releases The fixed releases are available at the normal locations. ### Credit This issue was responsibly reported by Hackerone researcher [fbettag](https://hackerone.com/fbettag).

O3 Security · Impact-Aware SCA

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