CVE-2026-63115

5.3 MEDIUM 0.1% exploit odds Fix listed Other Server

What it is

ActivityPub is a multi-tenant ActivityPub server for Ghost, built with Fedify. From 1.0.0 until 1.2.6, the `Undo` handler allows a remote federated server to cause the service to act on a `follow` or `repost` as though the activity came from a different account. This permits removal of an existing `follow` relationship or `repost` belonging to another account without that account's involvement. No private data is exposed and content is not modified; the affected relationships can be re-established. Services proxying to Ghost's hosted ActivityPub server have already been updated, while self-hosted services require an updated image and redeployment. This issue is fixed in version 1.2.6.

At a glance

Exploitability: Can be exploited over the network without logging in. Limited direct impact.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-10-30 22:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-02 19:18 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 5.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-30 22:16 UTC
Last modified: 2026-11-02 19:18 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-290
Record status: Awaiting Analysis

Attack profile CVSS 3.1 · 5.3

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-63115.md and follow it. Check whether this project is affected by CVE-2026-63115. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record