CVE-2026-28490 — Observable Discrepancy in Authlib

CWE-203 — Observable DiscrepancyCWE-327 — Use of a Broken or Risky Cryptographic AlgorithmCWE-325 — Missing Cryptographic Step7 documents6 sources
Severity
8.3HIGHNVD
EPSS
0.0%
top 98.56%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
AuthlibDebian Python-authlib
Timeline
PublishedMar 16

Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a cryptographic padding oracle vulnerability was identified in the Authlib Python library concerning the implementation of the JSON Web Encryption (JWE) RSA1_5 key management algorithm. Authlib registers RSA1_5 in its default algorithm registry without requiring explicit opt-in, and actively destroys the constant-time Bleichenbacher mitigation that the underlying cryptography library implements cor…

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

Affected Packages3 packages

▶debiandebian/python-authlib< python-authlib 1.6.9-1 (forky)
▶NVDauthlib/authlib< 1.6.9
▶PyPIauthlib/authlib< 1.6.9

Patches

Patch: github.com ↗

🔴Vulnerability Details

3
GHSA
Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle↗2026-03-16
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OSV
CVE-2026-28490: Authlib is a Python library which builds OAuth and OpenID Connect servers↗2026-03-16
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OSV
Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle↗2026-03-16
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📋Vendor Advisories

2
Red Hat
authlib: Authlib: Information disclosure due to cryptographic padding oracle in JWE RSA1_5↗2026-03-16
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Debian
CVE-2026-28490: python-authlib - Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior...↗2026
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🕵️Threat Intelligence

1
Wiz
CVE-2026-28490 Impact, Exploitability, and Mitigation Steps | Wiz↗
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