CVE-2026-28490

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure.

Exploit odds

0.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-03-16 18:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 10:28 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.1% in the next 30 days (EPSS).
• Severity: 8.3 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-03-16 18:16 UTC

Last modified

2026-06-17 10:28 UTC

Exploit probability

0.1% · EPSS, next 30 days

Weakness

CWE-203

Record status

Analyzed

Affected

• Authlib < 1.6.9

Attack profile CVSS 4.0 · 8.3

Attack vector

Network

Complexity

High

Attack requirements

Present

Privileges needed

None

User interaction

None

Confidentiality

High

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-28490.md and follow it. Check whether this project is affected by CVE-2026-28490. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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