CVE-2020-5261

mediumpriority · track · 28OT risk · elevatedEPSS 0.015 · 74 %ileEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.50% (74th) EPSS
CVSS 4.9 · medium
Is it mine?
3 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-27

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

8.2
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.9–8.2

v2.04.9mediumAV:N/AC:M/Au:S/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 6.8 · impact 4.9
v3.16.8mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:Nprimary · NVD / NIST USexploitability 1.6 · impact 5.2
v3.18.2highCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:Nsecondary · ENISA EU
v3.18.2highCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:Nsecondary · security-advisories@github.comexploitability 1.8 · impact 5.8
v3.18.2highCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:Nsecondary · OSV
v3.16.2mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-294USprimaryCWE-294US
03

affected products (3)

Products and version ranges known to be affected.

04

advisories (1)

Vendor and ecosystem advisories describing this.

  • GHSA-g6j2-ch25-5mmvMissing Token Replay Detection in Saml2 Authentication services for ASP.NET2020-03-25ghsa · osvUS

    ### 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: * Comment on #711. * Email us at [security@sustainsys.com](mailto:security@susatinsys.com) if you think that there are further security issues.

05

also known as (3)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdnvdosvNVDCVE.orgMITRE
published 2020-03-25modified 2026-06-17
08

references (10)

External citations — patches, advisories, analysis.

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