CVE-2025-62706

CVSS 6.5 Medium
  • CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  • Published: 2025-10-22T22:15:35.557
  • Last modified: 1761571233

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.

Related CVE by CWE

No related CWE found.

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Recently Exploited Similar Vulnerabilities

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How to fix CVE-2025-62706

CVE-2025-62706 is a medium severity vulnerability affecting the affected product.

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 […]

Exploit Difficulty: EASY
⏱️ Time to exploit: < 1 hour
🛠️ Required skills: Basic web security knowledge
💰 Public exploits: Likely available

How to Fix:

1 Identify affected systems

- Check if you're running the affected product

2 Immediate actions

- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access

3 Verification

- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)

4 Long-term prevention

- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations

Exploit Difficulty Assessment

EASY
⏱️ Time to Exploit: < 1 hour
🛠️ Skills Required: Basic web security knowledge
💰 Public Exploits: Likely available

Vulnerability Timeline

Oct 22, 2025
Vulnerability Published

CVE details first published to NVD database

Jan 01, 1970
Last Modified

CVE details were updated

Oct 28, 2025
Imported to Database

Added to this CVE tracking system

Detection Rules & IOCs

No specific detection rules generated for this vulnerability type.

No vendor/product data available.