CVE-2026-288029.1CriticalCWE-347

CVE-2026-28802: Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification

authlib

Fixed in 1.6.7 · Affected: authlib before 1.6.7 · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

45th percentile

050100

Higher than 45% of scored CVEs

9.1CriticalCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

authlib · authlib>= 1.6.5, < 1.6.7

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Verification of Cryptographic Signature · Cryptography
Vendor: authlib
Published: March 2026
Band: Unlikely (under 1%), March 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-28802 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.