Authlib : JWE zip=DEF decompression bomb enables DoS

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-62706
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-10-22 22:15:35 UTC
Updated2026-10-19 13:10:00 UTC
DescriptionAuthlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-400 | CWE-770 | CWE-400 CWE-400: Uncontrolled Resource Consumption | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Authlib Authlib All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Authlib Authlib affected < 1.6.5 Not specified

References

ReferenceSourceLinkTags
github.com/authlib/authlib/commit/e0863d5129316b1790eee5f14cece32a03b8184d [email protected] github.com Patch
github.com/authlib/authlib/security/advisories/GHSA-g7f3-828f-7h7m [email protected] github.com Exploit, Mitigation, Third Party Advisory
lists.debian.org/debian-lts-announce/2025/10/msg00032.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
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