CVE-2026-34148: Fedify unbounded redirect following resource exhaustion in document loader

CVE-2026-34148 · Severity: high · CVSS 7.5 · Published 2026-04-06

Fedify, a library used for building decentralized social media applications, is vulnerable to a denial-of-service attack. An attacker can provide a malicious link that forces the server into an infinite loop of web requests. This can exhaust the server's resources, leading to slow performance or a complete service outage for all users.

Technologies: Fedify, @fedify/fedify (npm). Vendors: Fedify, npm.

Quick answers

Is CVE-2026-34148 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-34148 being exploited in the wild.
How severe is CVE-2026-34148?
High severity, with a CVSS score of 7.5, published 6 April 2026.
Which products and versions are affected?
Fedify < 1.9.6, >= 1.10.0, < 1.10.5, >= 2.0.0, < 2.0.8, = 2.1.0; Fedify Vocab Runtime < 2.0.8, = 2.1.0; @fedify/fedify (npm) SEMVER:introduced=0,fixed=1.9.6; @fedify/vocab-runtime (npm) SEMVER:introduced=0,fixed=2.0.8.
Is there a fix for CVE-2026-34148?
Yes. @fedify/fedify (npm): upgrade to 1.9.6 or later; @fedify/vocab-runtime (npm): upgrade to 2.0.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-34148 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-34148?
Check whether you run Fedify, Fedify Vocab Runtime, @fedify/fedify (npm) or one of the others listed 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.

How to fix

  • @fedify/fedify (npm): upgrade to 1.9.6 or later
    npm install @fedify/fedify@1.9.6
  • @fedify/vocab-runtime (npm): upgrade to 2.0.8 or later
    npm install @fedify/vocab-runtime@2.0.8

Technical details

The vulnerability exists in the remote document loader and authenticated document loader of @fedify/fedify. These components recursively follow HTTP 3xx redirects without enforcing a maximum redirect count or implementing loop detection. An attacker can trigger this by providing a malicious ActivityPub keyId or actor URL that points to a self-referential redirect loop. Because failed lookups are only cached locally for the duration of a single request, the attack can be repeatedly executed to exhaust CPU, connection slots, and outbound bandwidth. Patches are available in versions 1.9.6, 1.10.5, 2.0.8, and 2.1.1.

Affected products

  • fedify-dev @fedify/fedify < 1.9.6, >= 1.10.0, < 1.10.5, >= 2.0.0, < 2.0.8, = 2.1.0
  • fedify-dev @fedify/vocab-runtime < 2.0.8, = 2.1.0

Identifiers

  • CVE-2026-34148
  • GHSA-gm9m-gwc4-hwgp

Timeline

  • 2026-04-04: disclosed: Initial publication by dahlia to fedify-dev/fedify
  • 2026-04-06: advisory: NVD publication date
  • 2026-04-07: advisory: GitHub Advisory Database publication date

References

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