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CVE-2025-65015VulnerabilityPublished Updated

Moto: joserfc has Possible Uncontrolled Resource Consumption Vulnerability Triggered by Logging Arbitrarily Large JWT

Affects motoSource GCVE Database

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Authoritative record:CVE-2025-65015· Critical 9.2

Not known to be exploited · CVSS 9.2 Critical : upgrade to 5.1.17 as a priority.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score
9.2Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.1.17
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade moto to 5.1.17.

Affected software

ProductAffectedFixed in
Homebrewmotopkg:brew/motoOther threatsAffected
  • >=5.1.13 <5.1.17
Fixed in
  • 5.1.17

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in joserfc version 5.1.17; upgrading to this version is recommended. Additionally, ensure that the web server or reverse proxy (e.g., nginx, uvicorn with appropriate settings) enforces strict limits on HTTP header sizes to prevent large JWT tokens from reaching the application. Applications running without a production-grade server or reverse proxy should implement such limits to mitigate this issue. No other specific mitigations are indicated by the vendor advisory.

Description

The joserfc Python JWT library has a vulnerability where logging error messages embeds non-decoded JWT token parts, allowing an attacker to cause uncontrolled resource consumption by sending arbitrarily large JWT bearer tokens. This can lead to excessively large log entries and memory usage during token decoding, especially if the web application is not protected by a production-grade web server or reverse proxy that enforces header size limits. The issue arises because the library raises an ExceededSizeError exception containing the full large payload, which is already loaded in memory. The vulnerability affects joserfc versions >=5.1.13 and <5.1.17 and is fixed in version 5.1.17.

References

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