Bug 2448162 (CVE-2026-28490)

Summary: CVE-2026-28490 authlib: Authlib: Information disclosure due to cryptographic padding oracle in JWE RSA1_5
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anthomas, bdettelb, dfreiber, doconnor, drow, dschmidt, ebourniv, ehelms, erezende, ggainey, hasun, jburrell, jkoehler, jlanda, juwatts, jwong, kshier, lgallett, lphiri, mhulan, nmoumoul, nyancey, omaciel, osousa, pcreech, ptisnovs, rchan, sbunciak, simaishi, smallamp, smcdonal, stcannon, teagle, tmalecek, ttakamiy, vkumar, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Authlib, a Python library for building OAuth and OpenID Connect servers. This cryptographic padding oracle vulnerability, affecting the JSON Web Encryption (JWE) RSA1_5 key management algorithm, could allow a remote attacker to decrypt sensitive information. The vulnerability arises because Authlib registers RSA1_5 without requiring explicit opt-in and bypasses constant-time Bleichenbacher mitigations in the underlying cryptography library.
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Description OSIDB Bzimport 2026-03-16 18:02:24 UTC
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.