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.NET
.NET NuGet
Not in CISA KEV
HIGH severity

CVE-2021-25976 — Piranha

HIGHFix: PiranhaCMS/piranha.core@e42abac

CVE-2021-25976 is a high-severity (CVSS 8.1) Cross-Site Request Forgery (CSRF) vulnerability in Piranha. A fix is available for Piranha — see the affected versions and patch details below.

Cross-Site Request Forgery in PiranhaCMS

Also known asGHSA-ppq7-88c7-q879
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2021-25976.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs40th percentile — riskier than 40% of all scored CVEsHighest risk
0.00%0.32%0.64%0.96%0.1%0.5%May 26Sep 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
.NETPiranha

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

In PiranhaCMS, versions 4.0.0-alpha1 to 9.2.0 are vulnerable to cross-site request forgery (CSRF) when performing various actions supported by the management system, such as deleting a user, deleting a role, editing a post, deleting a media folder etc., when an ID is known.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetPiranha≥ 4.0.0-alpha1&&< 10.0-alpha110.0-alpha1dotnet add package Piranha --version 10.0-alpha1

Affected Products

1 product · 12 configurations
Application
piranha cmsdotnetfoundation
≥ 4.0.1 && ≤ 9.2
1 version
4.0.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update Piranha to 10.0-alpha1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25976 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

In PiranhaCMS, versions 4.0.0-alpha1 to 9.2.0 are vulnerable to cross-site request forgery (CSRF) when performing various actions supported by the management system, such as deleting a user, deleting a role, editing a post, deleting a media folder etc., when an ID is known.
O3 Security · Impact-Aware SCA

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CVE-2021-25976: Piranha CSRF — Fixed in 10.0-alpha1