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TI-2025-38896 Aliases CVE-2025-62706GHSA-g7f3-828f-7h7m

Authlib : JWE zip=DEF decompression bomb enables DoS

Priority LOW 29CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 2 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00458 39th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial authlib (authlib): 1.6.5authlib (PyPI): 1.6.5Red Hat: 2 advisoriesRed Hat: 2 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
authlibauthlibbefore 1.6.51.6.5Patch availableCNA
—authlib (PyPI)before 1.6.51.6.5Patch availableGHSA-g7f3-828f-7h7m
  • authlib Vendorauthlib Affected before 1.6.5 Fixed in 1.6.5 Patch available CNA
  • authlib (PyPI) Vendor— Affected before 1.6.5 Fixed in 1.6.5 Patch available GHSA-g7f3-828f-7h7m

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*before 1.6.5Vulnerableauthlib
  • cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:* Versions before 1.6.5 Vulnerable ·authlib

Remediation

  • Fix · CNA authlib (authlib) Fixed in 1.6.5
  • Fix · GHSA-g7f3-828f-7h7m authlib (PyPI) Fixed in 1.6.5 Advisory →

Red Hat 2 advisories

  • RHSA-2026:1596 Released 2026-01-29 · Red Hat rating Important
    Red Hat Ansible Automation Platform 2.6 Container Release Update
    • Red Hat Ansible Automation Platform 2.6 registry.redhat.io/ansible-automation-platform-26/controller-rhel9, registry.redhat.io/ansible-automation-platform-26/controller-rhel9-operator, registry.redhat.io/ansible-automation-platform-26/de-minimal-rhel9 +7
  • RHSA-2026:0629 Released 2026-01-14 · Red Hat rating Important
    satellite/foreman-mcp-server-rhel9 container image available as a Technology Preview
    • Red Hat Satellite 6.18 registry.redhat.io/satellite/foreman-mcp-server-rhel9

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Ansible Automation Platform 2AffectedNo fix yet
Red Hat Ansible Automation Platform 2.6Fixed RHSA-2026:1596
Red Hat Satellite 6.18Fixed RHSA-2026:0629
Not affected: 2 products
  • Red Hat Ansible Automation Platform 2.6
  • Red Hat Quay 3

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-62706
  2. 2026-10-03 Alias added: GHSA-g7f3-828f-7h7m

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • TI-2026-22305 Authlib JWS JWK Header Injection: Signature Verification Bypass CVSS 3.1CRITICAL 9.1
  • TI-2026-79518 Authlib fix bypass lets attackers forge HS256 tokens with PEM keys CVSS 3.1CRITICAL 9.1
  • TI-2025-36973 Authlib: JWS/JWT accepts unknown crit headers (RFC violation → possible authz bypass) CVSS 3.1HIGH 7.5
  • TI-2024-25068 lepture Authlib before 1.3.1 has algorithm confusion with asymmetric public keys. CVSS 3.1HIGH 7.5
  • TI-2025-41738 Authlib: 1-click Account Takeover CVSS 3.1HIGH 8.8
  • TI-2026-22761 Authlib: Fail-Open Cryptographic Verification in OIDC Hash Binding CVSS 4.0HIGH 8.2
See all 18 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences