CVE-2025-62706
Publication date 24 October 2025
Last updated 24 October 2025
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| python-authlib | 25.10 questing |
Needs evaluation
|
| 25.04 plucky |
Needs evaluation
|
|
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy |
Needs evaluation
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
6.5 · Medium
|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |