CVE-2026-26078Network attack vector

Unauthorized pledge changes via empty-key webhook HMAC

Published Feb 26, 2026 · Updated Feb 26, 2026

Authentication bypass in Discourse before 2025.12.2, 2026.1.1, and 2026.2.0 allows remote attackers to alter Patreon pledge data. The Patreon webhook controller verifies attacker-chosen request bodies with HMAC-MD5 even when patreon_webhook_secret is blank, making the empty-key signature reproducible. Exposure requires the Patreon webhook endpoint and an unconfigured secret; forged payloads can create, modify, or delete pledges and trigger group synchronization.

CVSS severity7.5
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Discourse before 2025.12.2, 2026.1.1, and 2026.2.0 allows remote attackers to alter Patreon pledge data. The Patreon webhook controller verifies attacker-chosen request bodies with HMAC-MD5 even when patreon_webhook_secret is blank, making the empty-key signature reproducible. Exposure requires the Patreon webhook endpoint and an unconfigured secret; forged payloads can create, modify, or delete pledges and trigger group synchronization.

The record

CVE
CVE-2026-26078
Published
Feb 26, 2026
Updated
Feb 26, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-639, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record 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=< 2025.12.2
  2. Affected versionversion=>= 2026.1.0-latest, < 2026.1.1
  3. Affected versionversion=>= 2026.2.0-latest, < 2026.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Discourse · Discourseversion=< 2025.12.2; version=>= 2026.1.0-latest, < 2026.1.1; version=>= 2026.2.0-latest, < 2026.2.0

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
T1190Exploit Public-Facing Application

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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