How severe is GHSA-r657-rxjc-j557?

GHSA-r657-rxjc-j557 has a CVSS score of 5.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-r657-rxjc-j557?

GHSA-r657-rxjc-j557 affects the following packages: rack (RubyGems), rack (RubyGems), rack (RubyGems). Ecosystems affected: RubyGems.

How do I fix GHSA-r657-rxjc-j557?

Update rack to 2.2.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r657-rxjc-j557 is resolved across your whole dependency graph.

How do I detect GHSA-r657-rxjc-j557 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-r657-rxjc-j557 if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-r657-rxjc-j557?

O3 pinpoints whether GHSA-r657-rxjc-j557 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-r657-rxjc-j557 actively exploited in the wild?

No public exploit code has been indexed for GHSA-r657-rxjc-j557 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-r657-rxjc-j557?

GHSA-r657-rxjc-j557 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 35th 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-r657-rxjc-j557?

GHSA-r657-rxjc-j557 is classified as Information Exposure (CWE-200), CWE-441 (CWE-441), CWE-913 (CWE-913). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-r657-rxjc-j557 published, and has it been updated?

GHSA-r657-rxjc-j557 was published on October 10, 2025 and was last updated on February 4, 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

GHSA-r657-rxjc-j557

MEDIUM

Rack has a Possible Information Disclosure Vulnerability

Also known asCVE-2025-61780

Published

Oct 10, 2025

Updated

Feb 4, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk35th percentile+0.43%

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.

Blast Radius

3 pkgs affected

💎rack💎rack💎rack

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

Summary

A possible information disclosure vulnerability existed in Rack::Sendfile when running behind a proxy that supports x-sendfile headers (such as Nginx). Specially crafted headers could cause Rack::Sendfile to miscommunicate with the proxy and trigger unintended internal requests, potentially bypassing proxy-level access restrictions.

Details

When Rack::Sendfile received untrusted x-sendfile-type or x-accel-mapping headers from a client, it would interpret them as proxy configuration directives. This could cause the middleware to send a "redirect" response to the proxy, prompting it to reissue a new internal request that was not subject to the proxy's access controls.

An attacker could exploit this by:

Setting a crafted x-sendfile-type: x-accel-redirect header.
Setting a crafted x-accel-mapping header.
Requesting a path that qualifies for proxy-based acceleration.

Impact

Attackers could bypass proxy-enforced restrictions and access internal endpoints intended to be protected (such as administrative pages). The vulnerability did not allow arbitrary file reads but could expose sensitive application routes.

This issue only affected systems meeting all of the following conditions:

The application used Rack::Sendfile with a proxy that supports x-accel-redirect (e.g., Nginx).
The proxy did not always set or remove the x-sendfile-type and x-accel-mapping headers.
The application exposed an endpoint that returned a body responding to .to_path.

Mitigation

Upgrade to a fixed version of Rack which requires explicit configuration to enable x-accel-redirect:
```
use Rack::Sendfile, "x-accel-redirect"
```

Alternatively, configure the proxy to always set or strip the headers (you should be doing this!):

proxy_set_header x-sendfile-type x-accel-redirect;
proxy_set_header x-accel-mapping /var/www/=/files/;

Or in Rails applications, disable sendfile completely:
```
config.action_dispatch.x_sendfile_header = nil
```

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`rack`	all versions	2.2.20
💎RubyGems	`rack`	≥ 3.0&&< 3.1.18	3.1.18
💎RubyGems	`rack`	≥ 3.2&&< 3.2.3	3.2.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update rack to 2.2.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r657-rxjc-j557 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 pinpoints whether GHSA-r657-rxjc-j557 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-r657-rxjc-j557. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary A possible information disclosure vulnerability existed in `Rack::Sendfile` when running behind a proxy that supports `x-sendfile` headers (such as Nginx). Specially crafted headers could cause `Rack::Sendfile` to miscommunicate with the proxy and trigger unintended internal requests, potentially bypassing proxy-level access restrictions. ## Details When `Rack::Sendfile` received untrusted `x-sendfile-type` or `x-accel-mapping` headers from a client, it would interpret them as proxy configuration directives. This could cause the middleware to send a "redirect" response to the pro

O3 Security · Impact-Aware SCA

Is GHSA-r657-rxjc-j557 in your dependencies?

O3 detects GHSA-r657-rxjc-j557 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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