Quick answers
- Is CVE-2026-46348 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-46348 being exploited in the wild.
- How severe is CVE-2026-46348?
- Informational severity, with a CVSS score of 8.7, published 24 June 2026.
- Which products and versions are affected?
- Mastodon < 4.5.10, < 4.4.17, < 4.3.23.
- Is there a fix for CVE-2026-46348?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-46348 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-46348?
- Check whether you run Mastodon at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A Server-Side Request Forgery (SSRF) vulnerability exists in Mastodon due to an incomplete blocklist of private IP address ranges. Specifically, the validation logic failed to account for certain IPv6 address representations (such as the unspecified address '::') that can resolve to the local loopback interface. An unauthenticated remote attacker can provide a specially crafted URL that bypasses the 'ALLOWED_PRIVATE_ADDRESSES' filter. This allows the attacker to force the server to perform outbound HTTP requests to internal services or local interfaces. The issue is resolved in versions 4.5.10, 4.4.17, and 4.3.23 by updating the IP validation logic to include the missing ranges.
Affected products
- Mastodon Mastodon < 4.5.10, < 4.4.17, < 4.3.23
Timeline
- 2026-05-20: advisory: GitHub Security Advisory published
- 2026-06-24: disclosed: CVE published to NVD