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CVE-2020-5261

Missing Token Replay Detection

MEDIUM
6.8
CVSS Score
Published: March 25, 2020 at 01:15 AM UTC
Updated: June 17, 2026 at 03:21 AM UTC
1 product affected across 1 vendorSaml2

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Severity
MEDIUM6.8
Exploit prediction
EPSS 1%

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Saml2· Sustainsysnuget
95%
v < 2.5.02.0.0 ≤ v < 2.5.0
Affected range stops below 2.5.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/Sustainsys/Saml2/commit/e58e0a1aff2b1ead6aca080b7cdced55ee6d5241
x_refsource_MISCIssue TrackingThird Party Advisory
Source: [email protected]
https://github.com/Sustainsys/Saml2/issues/711
x_refsource_CONFIRMThird Party Advisory
Source: [email protected]
https://github.com/Sustainsys/Saml2/security/advisories/GHSA-g6j2-ch25-5mmv

CVSS

6.8MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-294

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