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NVD / CVE Program· CNA Mend

CVE-2021-25976: Piranha CMS - Site-wide Cross-Site Request Forgery (CSRF)

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.45% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: Piranha (NuGet) 10.0-alpha1.

Low priority for now. Upgrade to Piranha (NuGet) 10.0-alpha1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
Nov 16, 2021
Updated
Jun 16, 2026
EPSS
0.4% · 39th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
8.1
CNA · Mend
8.1
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-25976

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
dotnetfoundationpiranha cms

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • dotnetfoundation piranha cms4.0.1 and later · up to 9.2 inclusive
  • dotnetfoundation piranha cms4.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Mend). Independent of NVD's CPE analysis and usually ahead of it.

  • PiranhaCMS Piranha

    • 4.0.0-alpha1 and later · before unspecifiedaffected
    • unspecified and later · up to and including 9.2.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
NuGetPiranhafrom 4.0.0-alpha1 · before 10.0-alpha110.0-alpha1

Same product

dotnetfoundation: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-57692PiranhaCMS 12.0 allows stored XSS in the Text content block of Standard and Standard Archive Pages via /manager/pages, enabling execution of
    27Monitor
  • CVE-2025-67291A stored cross-site scripting (XSS) vulnerability in the Media module of Piranha CMS v12.1 allows attackers to execute arbitrary web scripts
    24Monitor
  • CVE-2025-67290A stored cross-site scripting (XSS) vulnerability in the Page Settings module of Piranha CMS v12.1 allows attackers to execute arbitrary web
    24Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-25977Oct 25, 2021 · Piranha CMS - Stored XSS in Page Title
    21Monitor
  • Later →CVE-2024-55342Dec 20, 2024 · A file upload functionality in Piranha CMS 11.1 allows authenticated remote attackers to upload a crafted PDF file to /manager/media.
    18Monitor
  • Later →CVE-2024-55341Dec 20, 2024 · A stored cross-site scripting (XSS) vulnerability in Piranha CMS 11.1 allows remote attackers to execute arbitrary JavaScript in the web bro
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
NuGet:Piranha10.0-alpha1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-352 · Cross-Site Request Forgery (CSRF)

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

nvd-primary

Root cause

State-changing requests rely on the session cookie the browser sends automatically; nothing verifies that the request came from the user’s own page.

The bug in code

The whole CWE-352 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
app.use(session({ cookie: { httpOnly: true } }));app.post("/account/address", updateAddress);

Fixed

ts
app.use(session({ cookie: { httpOnly: true, sameSite: "lax" } }));app.post("/account/address", csrfProtection, updateAddress);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records