CVE-2026-34148
HIGHCVE-2026-34148 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in @fedify/fedify. O3 Security confirms whether CVE-2026-34148 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Fedify affected by resource exhaustion caused by unbounded redirect following during remote key/document resolution
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
@fedify/fedifynpm@fedify/vocab-runtimenpmDescription
Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to 1.9.6, 1.10.5, 2.0.8, and 2.1.1, @fedify/fedify follows HTTP redirects recursively in its remote document loader and authenticated document loader without enforcing a maximum redirect count or visited-URL loop detection. An attacker who controls a remote ActivityPub key or actor URL can force a server using Fedify to make repeated outbound requests from a single inbound request, leading to resource consumption and denial of service. This vulnerability is fixed in 1.9.6, 1.10.5, 2.0.8, and 2.1.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fedify/fedify | all versions | 1.9.6 |
| 📦npm | @fedify/vocab-runtime | all versions | 2.0.8 |
| 📦npm | @fedify/vocab-runtime | ≥ 2.1.0&&< 2.1.1 | 2.1.1 |
| 📦npm | @fedify/fedify | ≥ 1.10.0&&< 1.10.5 | 1.10.5 |
| 📦npm | @fedify/fedify | ≥ 2.0.0&&< 2.0.8 | 2.0.8 |
| 📦npm | @fedify/fedify | ≥ 2.1.0&&< 2.1.1 | 2.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @fedify/fedify. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @fedify/fedify to 1.9.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34148 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-34148 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-34148. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-34148 in your dependencies?
O3 detects CVE-2026-34148 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.