CVE-2020-5261 json
Missing Token Replay Detection
published 2020-03-25 6 y ago modified 2026-07-08 4 mo ago also GHSA-g6j2-ch25-5mmv , EUVD-2020-0344
- cvss
- 8.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.5%
- EPSS 1.5% chance of exploitation in 30 days, percentile 74%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Exploit prediction
1.50% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.2 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N |
| NVD | 3.1 | 6.8 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N |
| NVD | 2.0 | 4.9 | AV:N/AC:M/Au:S/C:P/I:P/A:N |
| GitHub | 3.1 | 8.2 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| nuget | Sustainsys.Saml2 | >=2.0.0, <2.5.0 |
2.5.0 |
Affected products
- Sustainsys Saml2
Classification
- Weakness
-
- CWE-294 Authentication Bypass by Capture-replay
References
-
github.com
/Sustainsys/Saml2/commit/e58e0a1aff2b1ead6aca080b7cdced55ee6d5241
web, patch, third-party-advisory
-
github.com
/Sustainsys/Saml2/security/advisories/GHSA-g6j2-ch25-5mmv
web, third-party-advisory
-
github.com
/Sustainsys/Saml2/issues/711
web, issue-tracking, third-party-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2020-5261
advisory
Sources
- CVE List CVE-2020-5261
- GitHub Advisory GHSA-g6j2-ch25-5mmv
- NVD CVE-2020-5261
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