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Fencer Vulns
medium 6.5

CVE-2025-62706 json

Authlib : JWE zip=DEF decompression bomb enables DoS

published 2025-10-10 12 mo ago modified 2026-10-19 20 d ago also EUVD-2025-33799 , GHSA-g7f3-828f-7h7m , PYSEC-2026-1202

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

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.

Patch / fix

  • pypi authlib 1.6.5
  • authlib authlib 1.6.5
  • python-authlib Debian 12 1.2.0-1+deb12u1
  • python-authlib Debian 13 1.6.0-1+deb13u1
  • python-authlib Debian 14 1.6.5-1

debian advisories DEBIAN-CVE-2025-62706

  • python-authlib Ubuntu Pro 22.04 LTS 0.15.5-1ubuntu0.1~esm1
  • python-authlib Ubuntu Pro 24.04 LTS 1.3.0-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2025-62706

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-Authlib SLE Module for Python 3 15 SP7, SLE Module for Python 3 15 SP6, openSUSE Leap 15.6 1.3.1-150600.3.9.1

suse advisories SUSE-SU-2025:3842-1

  • python-Authlib openSUSE Tumbleweed 1.9.1-1.1

opensuse advisories openSUSE-SU-2026:12390-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-62706 updated cvss 6.5

authlib: Authlib : JWE zip=DEF decompression bomb enables DoS

  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-25/lightspeed-chatbot-rhel8
    affected: workaround, no fix available
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26 1768915992
    fixed: vendor fix RHSA-2026:1596
  • Red Hat Satellite 6.18 satellite 1767868827
    fixed: vendor fix RHSA-2026:0629
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform 1768951346, ansible-automation-platform 1768951348, ansible-automation-platform-26 1768509220, ansible-automation-platform-26 1768846975, ansible-automation-platform-26 1768853828, ansible-automation-platform-26 1768858596, +21 more Red Hat Quay 3 quay/quay-rhel8
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
12 mo ago

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/authlib/authlib/security/advisories/GHSA-g7f3-828f-7h7m referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi authlib
<1.6.5
1.6.5

Affected products

  • authlib authlib

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.