CVE-2021-39171

mediumpriority · track · 30EPSS 0.013 · 71 %ileEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.32% (71st) EPSS
CVSS 5 · medium
Is it mine?
3 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-22

Passport-SAML is a SAML 2.0 authentication provider for Passport, the Node.js authentication library. Prior to version 3.1.0, a malicious SAML payload can require transforms that consume significant system resources to process, thereby resulting in reduced or denied service. This would be an effective way to perform a denial-of-service attack. This has been resolved in version 3.1.0. The resolution is to limit the number of allowable transforms to 2.

01

cvss

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

7.5
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · ENISA EU
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · security-advisories@github.comexploitability 3.9 · impact 1.4
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · OSV
v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-400USCWE-400US
03

affected products (3)

Products and version ranges known to be affected.

04

advisories (1)

Vendor and ecosystem advisories describing this.

  • GHSA-5379-r78w-42h2Unlimited transforms allowed for signed nodes2021-08-30ghsa · osvUS

    ### Impact A malicious SAML payload can require transforms that consume significant system resources to process, thereby resulting in reduced or denied service. This would be an effective way to perform a denial-of-service attack. ### Patches This has been resolved in version 3.1.0. The resolution is to limit the number of allowable transforms to 2. ### References https://github.com/node-saml/passport-saml/pull/595

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 2021-08-27modified 2026-06-17
07

references (7)

External citations — patches, advisories, analysis.

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