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CVE-2026-28802

Authlib vulnerability

9.8 CRITICALPublic exploitEPSS 0.57%
  1. Published6 Mar 2026

Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Authlib≥ 1.6.5 < 1.6.7

Remediation

Fixed in
Authlib≥ 1.6.7

References

and 2 more references

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Frequently asked

Is CVE-2026-28802 being actively exploited?

CVE-2026-28802 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.57%.

How severe is CVE-2026-28802?

CVE-2026-28802 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.57% probability of exploitation.

Which products are affected by CVE-2026-28802?

Affected products include Authlib.

How do I fix CVE-2026-28802?

Upgrade affected software to a fixed version, for example Authlib 1.6.7 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-28802 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.