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Faraday: Uncontrolled recursion in NestedParamsEncoder allows stack exhaustion DoS via deeply nested query parameters

High severity GitHub Reviewed Published Jun 18, 2026 in lostisland/faraday • Updated Jun 26, 2026

Package

bundler faraday (RubyGems)

Affected versions

>= 2.0.0, <= 2.14.2
>= 1.0.0, <= 1.10.5

Patched versions

2.14.3
1.10.6

Description

Faraday::NestedParamsEncoder, the default nested query parameter encoder/decoder in Faraday, decodes nested query strings without enforcing a maximum nesting depth.

A crafted query string such as:

a[x][x][x][x]...[x]=1

causes Faraday to build a deeply nested Ruby Hash structure. The internal dehash routine then recursively walks this attacker-controlled structure without a depth limit. At sufficient depth, Ruby raises an uncaught SystemStackError (stack level too deep), crashing the calling thread or worker. This can lead to denial of service in applications that pass attacker-controlled query strings to Faraday's nested query parsing or URL-building paths.

This has been patched in version 2.14.3 and backported to 1.10.6.

References

@iMacTia iMacTia published to lostisland/faraday Jun 18, 2026
Published to the GitHub Advisory Database Jun 19, 2026
Reviewed Jun 19, 2026
Published by the National Vulnerability Database Jun 24, 2026
Last updated Jun 26, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(19th percentile)

Weaknesses

Uncontrolled Recursion

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. Learn more on MITRE.

CVE ID

CVE-2026-54297

GHSA ID

GHSA-98m9-hrrm-r99r

Source code

Credits

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