CVE-2020-5390Public exploitNetwork attack vector

Authentication bypass via mismatched assertion reference

Published Jan 13, 2020 · Updated Aug 4, 2024

XML signature wrapping in IdentityPython PySAML2 before 5.0.0 allows remote attackers to substitute unverified SAML assertion data. The _check_signature method accepts a Reference URI that identifies a different assertion instead of requiring the enclosing assertion's ID. No prior application privileges or user interaction are required, but a consumer must process an attacker-supplied signed SAML document.

CVSS severity8.7
High
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML signature wrapping in IdentityPython PySAML2 before 5.0.0 allows remote attackers to substitute unverified SAML assertion data. The _check_signature method accepts a Reference URI that identifies a different assertion instead of requiring the enclosing assertion's ID. No prior application privileges or user interaction are required, but a consumer must process an attacker-supplied signed SAML document.

The record

CVE
CVE-2020-5390
Published
Jan 13, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1606.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
8.7GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1606.002Forge Web Credentials: SAML Tokens

Public exploit references

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Technologies

Your stack

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Your stack

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