# CVE-2026-26973: Discourse doesn't scope reviewable notes to user-visible reviewables > Attackers with category moderation roles can modify notes on reviewables outside their scope when category group moderation is enabled. - **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 26 Feb 2026 - **Updated:** 26 Feb 2026 - **Also known as:** BIT-discourse-2026-26973, GHSA-c587-qx78-vhmx ## What is CVE-2026-26973? CVE-2026-26973 is a medium-severity missing authorization vulnerability in Discourse Discourse, published on 26 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim. ### Official description Discourse is an open source discussion platform. Versions prior to 2025.12.2, 2026.1.1, and 2026.2.0 have an IDOR (Insecure Direct Object Reference) in `ReviewableNotesController`. When `enable_category_group_moderation` is enabled, a user belonging to a category moderation group can create or delete their own notes on **any** reviewable in the system, including reviewables in categories they do not moderate. The controller used an unscoped `Reviewable.find` and the `ensure_can_see` guard only checked whether the user could access the review queue in general, not whether they could access the specific reviewable. Only instances with `enable_category_group_moderation` enabled are affected. Staff users (admins/moderators) are not impacted as they already have access to all reviewables. The issue is patched in versions 2025.12.2, 2026.1.1, and 2026.2.0 by scoping the reviewable lookup through `Reviewable.viewable_by(current_user)`. As a workaround, disable the `enable_category_group_moderation` site setting. This removes the attack surface as only staff users will have access to the review queue. Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key), CWE-863 (Incorrect Authorization) ## Which versions are affected by CVE-2026-26973? 1 open source package ship an affected version, including discourse. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `discourse` | Bitnami | All versions | 2025.12.2, 2026.1.1 | Products: Discourse Discourse. ## How do I fix CVE-2026-26973? Upgrade discourse to a fixed version for your release line: 2025.12.2 or 2026.1.1. ## Is CVE-2026-26973 being exploited? There is no known exploitation of CVE-2026-26973 in the wild and no public exploit code. ## Other vulnerabilities in Discourse Discourse - [CVE-2021-41163](https://insights.sbomify.com/CVE-2021-41163/): RCE via malicious SNS subscription payload (critical 10.0) - [CVE-2022-36066](https://insights.sbomify.com/CVE-2022-36066/): Discourse vulnerable to RCE via admins uploading maliciously zipped file (critical 9.1) - [CVE-2022-39356](https://insights.sbomify.com/CVE-2022-39356/): Discourse user account takeover via email and invite link (high 8.9) - [CVE-2023-22468](https://insights.sbomify.com/CVE-2023-22468/): Discourse vulnerable to Cross-site Scripting in local oneboxes (high 8.8) - [CVE-2026-27934](https://insights.sbomify.com/CVE-2026-27934/): Discourse leaks private topic title and post excerpt via user action API endpoint (high 8.7) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-26973 and fix it if it is affected. What it is: CVE-2026-26973 is a medium-severity missing authorization vulnerability in Discourse Discourse, published on 26 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-26973 in the wild and no public exploit code. Affected packages and fixed versions: - discourse (Bitnami): affected all versions; fixed in 2025.12.2, 2026.1.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-26973/ (Markdown: https://insights.sbomify.com/CVE-2026-26973/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-26973 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-26973 - OSV: https://osv.dev/vulnerability/CVE-2026-26973 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-26973/ Summaries are generated and may contain mistakes; the official description above is the record.