CVE-2020-5268

mediumpriority · track · 29EPSS 0.011 · 65 %ileEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.09% (65th) EPSS
CVSS 4.9 · medium
Is it mine?
6 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-27

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.

01

cvss

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

7.3
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.9–7.3

v2.04.9mediumAV:N/AC:M/Au:S/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 6.8 · impact 4.9
v3.17.3highCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:Nprimary · NVD / NIST USexploitability 2.1 · impact 5.2
v3.16.5mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:Nsecondary · ENISA EU
v3.16.5mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:Nsecondary · security-advisories@github.comexploitability 1.3 · impact 4.7
v3.16.5mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:Nsecondary · OSV
v3.16.7mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-287USprimaryCWE-303USCWE-303US
03

affected products (6)

Products and version ranges known to be affected.

04

advisories (1)

Vendor and ecosystem advisories describing this.

  • GHSA-9475-xg6m-j7pwSubject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET2020-04-22ghsa · osvUS

    ### Impact 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 tocken to create a log in session. ### Patches Version 1.0.2 and 2.7.0 are patched. ### Workarounds Ensure that any IdentityProvider trusted by the Sustainsys.Saml2 SP only issues bearer tokens if the audience matches the Sustainsys.Saml2 SP. ### For more information If you have any questions or comments about this advisory: * Comment on #103 * Email us at security@sustainsys.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 2020-04-21modified 2026-06-17
08

references (13)

External citations — patches, advisories, analysis.

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