CVE-2020-5261

8.2 HIGH 1% exploit odds Fix listed

What it is

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.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering.
Exploit odds: 1.5% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2020-03-25 02:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 03:21 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 1.5% in the next 30 days (EPSS).
Severity: 8.2 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2020-03-25 02:15 UTC
Last modified: 2026-06-17 03:21 UTC
Exploit probability: 1.5% · EPSS, next 30 days
Weakness: CWE-294
Record status: Modified

Affected

Sustainsys saml2 < 2.5.0

Attack profile CVSS 3.1 · 8.2

Attack vector: Network
Complexity: High
Privileges needed: Low
User interaction: None
Scope: Changed
Confidentiality: High
Integrity: High
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-5261.md and follow it. Check whether this project is affected by CVE-2020-5261. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record