How severe is CVE-2021-39171?

CVE-2021-39171 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-39171 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39171?

CVE-2021-39171 affects Passport-saml Project Passport-saml. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39171?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-39171 published?

CVE-2021-39171 was published on 2021-08-27 and last updated on 2026-06-17.

CVE-2021-39171

CVE-2021-39171 is a medium-severity vulnerability in Passport-saml Project Passport-saml with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Passport-saml Project Passport-saml
Published: 2021-08-27
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-39171?: 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.
How severe is CVE-2021-39171?: CVE-2021-39171 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-39171 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39171?: CVE-2021-39171 affects Passport-saml Project Passport-saml. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39171?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39171 published?: CVE-2021-39171 was published on 2021-08-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:passport-saml_project:passport-saml:*:*:*:*:*:node.js:*:*

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