CVE-2025-62706

MEDIUM EPSS 33.5%
Published Oct 22, 20258mo ago · Modified Jun 17, 20261w ago
6.5 CVSS 3.1
Medium
Find Similar
Published Oct 22, 2025 8mo ago
Last Modified Jun 17, 2026 1w ago

Description

Authlib 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.

CVSS Details

Base Score
6.5
Exploitability
2.8
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
33.5% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 2

CWE-400 Uncontrolled Resource Consumption Resource Mgmt
CWE-770

Affected Products 1

VendorProductVersionRange
authlibauthlib* <1.6.5

References 3

  • github.com https://github.com/authlib/authlib/commit/e0863d5129316b1790eee5f14cece32a03b8184d
    Patch
  • github.com https://github.com/authlib/authlib/security/advisories/GHSA-g7f3-828f-7h7m
    ExploitMitigationThird Party Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/10/msg00032.html

Remediation

  • github.com https://github.com/authlib/authlib/commit/e0863d5129316b1790eee5f14cece32a03b8184d
    Patch