# CVE-2026-53950: @tryghost/activitypub: XSS in Ghost's ActivityPub client

> An attacker can inject JavaScript into Ghost posts via a malicious ActivityPub server, potentially compromising user sessions or data.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** BIT-ghost-2026-53950, GHSA-xpp7-93x6-v29m

## What is CVE-2026-53950?

CVE-2026-53950 is a high-severity cross-site scripting vulnerability in TryGhost Ghost, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

@tryghost/activitypub is Ghost’s social/federation client app. Prior to 3.1.0, the ActivityPub client in Ghost was vulnerable to JavaScript injection on posts shared by a maliciously customised ActivityPub server. This vulnerability is fixed in 3.1.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-53950?

3 open source packages ship an affected version, including @tryghost/activitypub and ghost.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@tryghost/activitypub` | npm | All versions | 3.1.0 |
| `@tryghost/activitypub` | npm | All versions | 3.1.0 |
| `ghost` | Bitnami | All versions | 3.1.0 |

## How do I fix CVE-2026-53950?

Upgrade @tryghost/activitypub to 3.1.0 or later.

## Is CVE-2026-53950 being exploited?

There is no known exploitation of CVE-2026-53950 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53950 and fix it if it is affected.

What it is: CVE-2026-53950 is a high-severity cross-site scripting vulnerability in TryGhost Ghost, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-53950 in the wild and no public exploit code.

Affected packages and fixed versions:
- @tryghost/activitypub (npm): affected all versions; fixed in 3.1.0
- @tryghost/activitypub (npm): affected all versions; fixed in 3.1.0
- ghost (Bitnami): affected all versions; fixed in 3.1.0

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-2026-53950/ (Markdown: https://insights.sbomify.com/CVE-2026-53950/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53950
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53950
- OSV: https://osv.dev/vulnerability/CVE-2026-53950

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53950/
Summaries are generated and may contain mistakes; the official description above is the record.