How severe is GHSA-g6j2-ch25-5mmv?

GHSA-g6j2-ch25-5mmv has a CVSS score of 8.2/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-g6j2-ch25-5mmv?

GHSA-g6j2-ch25-5mmv affects the following packages: Sustainsys.Saml2 (NuGet). Ecosystems affected: NuGet.

How do I fix GHSA-g6j2-ch25-5mmv?

Update Sustainsys.Saml2 to 2.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g6j2-ch25-5mmv is resolved across your whole dependency graph.

How do I detect GHSA-g6j2-ch25-5mmv in my NuGet dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Sustainsys.Saml2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-g6j2-ch25-5mmv if there is no patch (or I can't update yet)?

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.

Is GHSA-g6j2-ch25-5mmv actively exploited in the wild?

No public exploit code has been indexed for GHSA-g6j2-ch25-5mmv yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-g6j2-ch25-5mmv?

GHSA-g6j2-ch25-5mmv has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 74th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-g6j2-ch25-5mmv?

GHSA-g6j2-ch25-5mmv is classified as CWE-294 (CWE-294). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-g6j2-ch25-5mmv published, and has it been updated?

GHSA-g6j2-ch25-5mmv was published on March 25, 2020 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

.NET

.NET NuGet

Not in CISA KEV

HIGH severity

Missing Token Replay Detection in Saml2 Authentication services for ASP.NETGHSA-g6j2-ch25-5mmv

HIGHFix: Sustainsys/Saml2@e58e0a1

GHSA-g6j2-ch25-5mmv is a high-severity (CVSS 8.2) CWE-294 vulnerability in Sustainsys.Saml2. A fix is available for Sustainsys.Saml2 — see the affected versions and patch details below.

Also known asCVE-2020-5261

Published

Mar 25, 2020

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs74th percentile — riskier than 74% of all scored CVEsHighest risk

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

.NETSustainsys.Saml2

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

Saml2 Authentication services for ASP.NET (NuGet package Sustainsys.Saml2) greater than 2.0.0, and less than version 2.5.0 has a faulty implementation of Token Replay Detection. Token Replay Detection is an important defence in depth measure for Single Sign On solutions. The 2.5.0 version is patched. Note that version 1.0.1 is not affected. It has a correct Token Replay Implementation and is safe to use. Saml2 Authentication services for ASP.NET (NuGet package Sustainsys.Saml2) greater than 2.0.0, and less than version 2.5.0 have a faulty implementation of Token Replay Detection. Token Replay Detection is an important defense measure for Single Sign On solutions. The 2.5.0 version is patched. Note that version 1.0.1 and prior versions are not affected. These versions have a correct Token Replay Implementation and are safe to use.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`Sustainsys.Saml2`	≥ 2.0.0&&< 2.5.0	2.5.0`dotnet add package Sustainsys.Saml2 --version 2.5.0`

Affected Products

1 product · 1 configurations

Application

saml2sustainsys

≥ 2.0.0 && < 2.5.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Sustainsys.Saml2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Sustainsys.Saml2 to 2.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g6j2-ch25-5mmv 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.

Frequently Asked Questions

### Impact Token Replay Detection is an important defence in depth measure for Single Sign On solutions. In all previous 2.X versions, the Token Replay Detection is not properly implemented. Note that version 1.0.1 is not affected. It has a correct Token Replay Implementation and is safe to use. ### Patches The 2.5.0 version is patched. ### Workarounds There are no workarounds with existing versions. Fixing the issue requires code updates. ### References https://en.wikipedia.org/wiki/Replay_attack ### For more information If you have any questions or comments about this advisory: * Comme