Cyber Resilience

CVE-2026-28219

Discourse ≤ 2025.12.2

Published
26 February 2026
Modified
02 March 2026
Patch / advisory
View advisory
CVSS Score v4 1.3
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0020 9th percentile
Risk Priority 24 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-28219 is a low-severity Improperly Controlled Modification of Dynamically-Determined Object Attributes (CWE-915) vulnerability in Discourse Discourse. Its CVSS base score is 1.3 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-6 (Least Privilege) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A08:2025 Software or Data Integrity Failures

EU & UK References

Vulnerability Data

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, an improper authorization check in the topic management logic allows authenticated users to modify privileged attributes of their topics. By manipulating specific parameters in a PUT…

more

or POST request, a regular user can elevate a topic’s status to a site-wide notice or banner, bypassing intended administrative restrictions. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. There are no practical workarounds to prevent this behavior other than applying the security patch. Administrators concerned about unauthorized promotions should audit recent changes to site banners and global notices until the fix is deployed.

CWE(s)
CWE-915

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1098 Account Manipulation Persistence
Adversaries may manipulate accounts to maintain and/or elevate access to victim systems.
attack.mitre.org →
T1098.001 Additional Cloud Credentials Persistence
Adversaries may add adversary-controlled credentials to a cloud account to maintain persistent access to victim accounts and instances within the environment.
attack.mitre.org →
T1098.003 Additional Cloud Roles Persistence
An adversary may add additional roles or permissions to an adversary-controlled cloud account to maintain persistent access to a tenant.
attack.mitre.org →
T1098.004 SSH Authorized Keys Persistence
Adversaries may modify the SSH <code>authorized_keys</code> file to maintain persistence on a victim host.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-27151Same product: Discourse Discourse
CVE-2026-33423Same product: Discourse Discourse
CVE-2024-36113Same product: Discourse Discourse
CVE-2026-21865Same product: Discourse Discourse
CVE-2026-33514Same product: Discourse Discourse
CVE-2026-33408Same product: Discourse Discourse
CVE-2026-29072Same product: Discourse Discourse
CVE-2026-30889Same product: Discourse Discourse
CVE-2026-26207Same product: Discourse Discourse
CVE-2026-26979Same product: Discourse Discourse

Affected Assets

discourse
discourse
2026.2.0 · ≤ 2025.12.2 · 2026.1.0 — 2026.1.1

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

Enforces authorizations so that only permitted attributes may be modified on an object.

AC-6 Least Privilege good match

Limits the set of modifiable attributes a subject is authorized to touch.

SI-10 Information Input Validation good match

Validates incoming attribute names and values so that only explicitly allowed fields are accepted for update.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require allow-listing of mutable object attributes and input validation to block mass-assignment flaws.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match
prevents

Secure coding standards explicitly forbid unsafe dynamic attribute assignment and require property allow-lists.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect mass-assignment flaws but does not itself prevent them at runtime.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle requires input validation and object-property whitelisting that directly mitigates mass-assignment risks.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit rules for allowable object attributes and safe deserialization.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles mandate strict control over dynamic object modification and attribute binding.

A.8.3 Information access restriction partial match
prevents

Information access restriction limits who can modify objects but does not address which attributes may be changed.

References