CVE-2026-54171 is a medium-severity (CVSS 6.5) CWE-201 vulnerability in excon. A fix is available for excon — see the affected versions and patch details below.
Excon: redact additional sensitive/risky headers when following redirects
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 CVE-2026-54171.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-54171 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
exconReal-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 redirect follower middleware previously failed to strip a number of headers that are known to be sensitive and did not provide a way to provide a custom list of headers to strip.
What kind of vulnerability is it? Who is impacted? This could cause inadvertent leakage of sensitive data for users of the RedirectFollower middleware in cases where the initial request includes header information that is not intended for the new target.
Patches
Patch exists and is released in v1.5.0
Workarounds
Users can backport the fix to a custom redirect follower middleware.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | excon | all versions | 1.5.0bundle update excon --conservative |
Affected Products
exconexcon_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for excon, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update excon to 1.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54171 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.
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.
This flaw in the Excon Ruby HTTP client library could lead to information disclosure. When applications using Excon follow HTTP redirects, sensitive headers from the initial request might be inadvertently sent to the new target, potentially exposing confidential data. This risk is present in Red Hat products that…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for CVE-2026-54171 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-54171 in your dependencies?
Find it across RubyGems, including transitive dependencies.