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CVE-2025-65015— joserfc has Possible Uncontrolled Resource Consumption Vulnerability Triggered by Logging Arbitrarily Large JWT Token Payloads

Quick assessment

Affected
authlib joserfc
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

joserfc是Authlib开源的一个Python库。 joserfc 1.3.3版本至1.3.5之前版本和1.4.0版本至1.4.2之前版本存在安全漏洞，该漏洞源于ExceededSizeError异常消息嵌入未解码JWT令牌部分，可能导致记录任意大的伪造JWT负载。

AI Predicted 6.5 Difficulty: Easy EPSS 0.41% · P33

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2025-65015

Vulnerability Information
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Vulnerability Title
joserfc has Possible Uncontrolled Resource Consumption Vulnerability Triggered by Logging Arbitrarily Large JWT Token Payloads
Source: CVE Program / CVE List V5
Vulnerability Description
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions from 1.3.3 to before 1.3.5 and from 1.4.0 to before 1.4.2, the ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT payload. In situations where a misconfigured — or entirely absent — production-grade web server sits in front of a Python web application, an attacker may be able to send arbitrarily large bearer tokens in the HTTP request headers. When this occurs, Python logging or diagnostic tools (e.g., Sentry) may end up processing extremely large log messages containing the full JWT header during the joserfc.jwt.decode() operation. The same behavior also appears when validating claims and signature payload sizes, as the library raises joserfc.errors.ExceededSizeError() with the full payload embedded in the exception message. Since the payload is already fully loaded into memory at this stage, the library cannot prevent or reject it. This issue has been patched in versions 1.3.5 and 1.4.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
joserfc 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
joserfc是Authlib开源的一个Python库。 joserfc 1.3.3版本至1.3.5之前版本和1.4.0版本至1.4.2之前版本存在安全漏洞，该漏洞源于ExceededSizeError异常消息嵌入未解码JWT令牌部分，可能导致记录任意大的伪造JWT负载。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
authlib joserfc >= 1.3.3, < 1.3.5 -

II. Public POCs for CVE-2025-65015

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III. Intelligence Information for CVE-2025-65015

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Patches & Fixes for CVE-2025-65015 (1)

Vendor Advisories for CVE-2025-65015 (1)

IV. Related Vulnerabilities

Same product: joserfc
Same vendor: authlib
Same weakness: CWE-770

V. Comments for CVE-2025-65015

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