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MEDIUM severity

CVE-2021-29435 — trestle-auth

MEDIUMFix: TrestleAdmin/trestle-auth@cb95b05

CVE-2021-29435 is a medium-severity (CVSS 6.5) Cross-Site Request Forgery (CSRF) vulnerability in trestle-auth. A fix is available for trestle-auth — see the affected versions and patch details below.

Cross-Site Request Forgery (CSRF) in trestle-auth

Also known asGHSA-h8hx-2c5r-32cf
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs50th percentile — riskier than 50% of all scored CVEsHighest risk
0.00%0.39%0.78%1.16%0.1%0.7%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-29435 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
💎trestle-auth

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

A vulnerability in trestle-auth versions 0.4.0 and 0.4.1 allows an attacker to create a form that will bypass Rails' built-in CSRF protection when submitted by a victim with a trestle-auth admin session. This potentially allows an attacker to alter protected data, including admin account credentials.

Patches

The vulnerability has been fixed in trestle-auth 0.4.2 released to RubyGems.

For more information

If you have any questions or comments about this advisory:

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemstrestle-auth≥ 0.4.0&&< 0.4.20.4.2bundle update trestle-auth --conservative

Affected Products

1 product · 2 configurations
Application
trestle-authtrestle-auth_project
2 versions
0.4.00.4.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update trestle-auth to 0.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29435 is resolved across your whole dependency graph.

  3. 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.

Frequently Asked Questions

### Impact A vulnerability in trestle-auth versions 0.4.0 and 0.4.1 allows an attacker to create a form that will bypass Rails' built-in CSRF protection when submitted by a victim with a trestle-auth admin session. This potentially allows an attacker to alter protected data, including admin account credentials. ### Patches The vulnerability has been fixed in trestle-auth 0.4.2 released to RubyGems. ### For more information If you have any questions or comments about this advisory: * Open an issue in [trestle-auth](https://github.com/TrestleAdmin/trestle-auth/issues) * Email the maintainer at
O3 Security · Impact-Aware SCA

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CVE-2021-29435: trestle-auth CSRF — Fixed in 0.4.2