CVE-2025-68659Network attack vector

Service degradation via oversized username-change requests

Published Jan 28, 2026 · Updated Jan 28, 2026

Denial of service in Discourse affected releases allows remote authenticated users to degrade forum performance via oversized JSON requests. The username preference endpoint PUT /u/{username}/preferences/username accepts large JSON bodies without effective resource limits, consuming server capacity during request handling. A valid low-privileged account is required, and successful requests produce noticeable delays and resource exhaustion that degrade other users and endpoints.

CVSS severity5.3
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Discourse affected releases allows remote authenticated users to degrade forum performance via oversized JSON requests. The username preference endpoint PUT /u/{username}/preferences/username accepts large JSON bodies without effective resource limits, consuming server capacity during request handling. A valid low-privileged account is required, and successful requests produce noticeable delays and resource exhaustion that degrade other users and endpoints.

The record

CVE
CVE-2025-68659
Published
Jan 28, 2026
Updated
Jan 28, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=>= 2025.11.0-latest, < 2025.11.2
  2. Affected versionversion=>= 2025.12.0-latest, < 2025.12.1
  3. Affected versionversion=>= 2026.1.0-latest, < 2026.1.0
  4. Affected versionversion=< 3.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=>= 2025.11.0-latest, < 2025.11.2; version=>= 2025.12.0-latest, < 2025.12.1; version=>= 2026.1.0-latest, < 2026.1.0; version=< 3.5.4

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
4.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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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