GHSA-chgm-3698-jm42: Ghost: Member existence leak via magic link sign-in response
Impact
A discrepancy in responses from the members signin endpoints made it possible for an unauthenticated attacker to determine whether a given email address belongs to a registered member of a Ghost site.
Vulnerable versions
This vulnerability is present in Ghost from v5.18.0 up to v6.21.0.
Patches
v6.21.1 contains a fix for this issue.
How to update
For self-hosters using Docker, find Docker's official Ghost image here. Updating a Docker-based Ghost instance is documented here.
If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here.
For more information
If you have any questions or comments about this advisory, email Ghost at security@ghost.org.
Details
Original advisory: https://github.com/advisories/GHSA-chgm-3698-jm42
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-539470.21% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 11% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-53947 | coverage & exploitation status | NVD · CVE.org |
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