CVE-2026-28490
Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle
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 correctly. This issue has been patched in version 1.6.9.
INFO
Published Date :
March 16, 2026, 6:16 p.m.
Last Modified :
March 16, 2026, 6:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-28490
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Authlib to version 1.6.9 or later.
- Verify JWE RSA1_5 algorithm implementation.
- Ensure constant-time mitigations are active.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-28490.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-28490 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-28490
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-28490 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-28490 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Mar. 16, 2026
Action Type Old Value New Value Added 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 correctly. This issue has been patched in version 1.6.9. Added CVSS V4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-327 Added CWE CWE-203 Added Reference https://github.com/authlib/authlib/commit/48b345f29f6c459f11c6a40162b6c0b742ef2e22 Added Reference https://github.com/authlib/authlib/releases/tag/v1.6.9 Added Reference https://github.com/authlib/authlib/security/advisories/GHSA-7432-952r-cw78