CVE-2025-62706 | Authlib : JWE zip=DEF decompression bomb enables DoS

Exp

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.

Published: 2025-10-22 Last update: 2025-11-03 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2025-62706 is rated Exploit Available (51.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.12%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-62706

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-62706

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-20 0.17% 0.12% -0.05%
2 2026-02-21 0.07% 0.17% +0.10%
3 2025-11-21 0.07%

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-62706

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
2.8 3.6 [email protected]

Weakness enumeration for CVE-2025-62706

GitHub Security Advisory for CVE-2025-62706

GHSA-g7f3-828f-7h7m · Severity: medium · Ecosystem: pip — Authlib : JWE zip=DEF decompression bomb enables DoS

OS Trackers for CVE-2025-62706

vendor priority summary link
debian not yet assigned CVE-2025-62706 not yet assigned priority: Debian including 1 source packages (python-authlib), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-62706
redhat medium https://access.redhat.com/security/cve/CVE-2025-62706
suse medium CVE-2025-62706 severity moderate: SUSE including 1 source package names (python311-Authlib-1.3.1-150600.3.9.1), 3 product×package rows across 3 product lines (SUSE Linux Enterprise Module for Python 3 15 SP6, SUSE Linux Enterprise Module for Python 3 15 SP7, openSUSE Leap 15.6): Fixed 3. https://www.suse.com/security/cve/CVE-2025-62706/
ubuntu medium CVE-2025-62706 medium priority: Ubuntu including 1 source packages (python-authlib), 5 status rows across 5 suites (jammy, noble, plucky, questing, upstream): released 3, ignored 1, needed 1. https://ubuntu.com/security/CVE-2025-62706

Affected software / configurations for CVE-2025-62706

Vendor Product Version Raw CPE
authlib authlib < 1.6.5 cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*

References for CVE-2025-62706

cvelogic Threat Intelligence