CVE-2025-65015Public exploitNetwork attack vector

Service interruption via oversized JWT exception logging

Published Nov 18, 2025 · Updated Nov 19, 2025

Resource exhaustion in Authlib joserfc 1.3.3 through 1.3.4 and 1.4.0 through 1.4.1 allows remote attackers to interrupt service. JWS and JWE registry size validators place complete attacker-controlled token segments into ExceededSizeError messages consumed by logging systems. Exploitation requires an application to accept an oversized JWT and log the exception without an effective upstream request-size limit.

CVSS severity9.2
Critical
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Authlib joserfc 1.3.3 through 1.3.4 and 1.4.0 through 1.4.1 allows remote attackers to interrupt service. JWS and JWE registry size validators place complete attacker-controlled token segments into ExceededSizeError messages consumed by logging systems. Exploitation requires an application to accept an oversized JWT and log the exception without an effective upstream request-size limit.

The record

CVE
CVE-2025-65015
Published
Nov 18, 2025
Updated
Nov 19, 2025
Vendor
Authlib
Product
joserfc
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.3.3, < 1.3.5
  2. Affected versionversion=>= 1.4.0, < 1.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Authlib · joserfcversion=>= 1.3.3, < 1.3.5; version=>= 1.4.0, < 1.4.2

Published CVSS scores

9.2GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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