CVE-2020-5268
Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
In Saml2 Authentication Services for ASP.NET versions before 1.0.2, and between 2.0.0 and 2.6.0, there is a vulnerability in how tokens are validated in some cases. Saml2 tokens are usually used as bearer tokens - a caller that presents a token is assumed to be the subject of the token. There is also support in the Saml2 protocol for issuing tokens that is tied to a subject through other means, e.g. holder-of-key where possession of a private key must be proved. The Sustainsys.Saml2 library incorrectly treats all incoming tokens as bearer tokens, even though they have another subject confirmation method specified. This could be used by an attacker that could get access to Saml2 tokens with another subject confirmation method than bearer. The attacker could then use such a token to create a log in session. This vulnerability is patched in versions 1.0.2 and 2.7.0.
Timeline
ID reserved
By GitHub_M
- 4 months later
· 4 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N |
| NVDNVD · Modified | 3.1 | High7.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 1.1% · top 35% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Weakness
Affected products
- affected < 1.0.2
- affected >= 2.0.0, <= 2.6.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- NuGetSustainsys.Saml2GHSA-9475-xg6m-j7pw (opens in a new tab)
References (4)
- https://github.com/Sustainsys/Saml2/commit/e58e0a1aff2b1ead6aca080b7cdced55ee6d5241 (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/Sustainsys/Saml2/security/advisories/GHSA-9475-xg6m-j7pw (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/Sustainsys/Saml2/issues/712 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.nuget.org/packages/Sustainsys.Saml2/ (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-9475-xg6m-j7pw (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-5268)Record last updated .