CVE-2026-34950 — AI Deep Analysis Summary

🚨 **Essence**: A flaw in `fast-jwt` allows bypassing the `^` anchor in `publicKeyPemMatcher` via leading spaces in the key string.…

🛡️ **Root Cause**: Improper input validation in the PEM key matcher regex. 🐛 **Flaw**: The `^` anchor is bypassed by prepending spaces to the public key string.…

🏢 **Vendor**: Nearform. 📦 **Product**: fast-jwt (JSON Web Token implementation). 📅 **Affected Versions**: Version 6.1.0 and all prior versions.

💀 **Attack**: JWT Algorithm Confusion. 🔓 **Impact**: Attackers can forge tokens or bypass authentication. 📊 **Severity**: High Confidentiality (C:H) and High Integrity (I:H) impact. No direct Availability (A:N) loss.

⚡ **Threshold**: Low. 🌐 **Network**: Network Accessible (AV:N). 🔑 **Auth**: No Privileges Required (PR:N). 👤 **User**: No User Interaction Needed (UI:N). 📈 **Complexity**: Low (AC:L).

🔍 **Public Exploit**: No specific PoC provided in the data. 📂 **Source**: Advisory confirmed via GitHub Security Advisories (GHSA-mvf2-f6gm-w987). ⚠️ **Risk**: Theoretical but highly likely given the low complexity.

🔎 **Check**: Scan for `fast-jwt` library usage in Node.js projects. 📋 **Version**: Verify if version is ≤ 6.1.0. 🔍 **Code**: Look for custom PEM key handling that might allow leading whitespace injection.

🛠️ **Fix**: Upgrade `fast-jwt` to a version > 6.1.0. 📢 **Official**: Patch released via Nearform GitHub Security Advisories. ✅ **Status**: Confirmed fix available.

🚧 **Workaround**: If upgrading isn't possible, strictly sanitize public key inputs to remove leading/trailing whitespace before passing to the JWT library.…

🔥 **Urgency**: HIGH. 🚨 **Priority**: Immediate patching recommended. 📉 **CVSS**: High severity (C:H, I:H). ⏳ **Time**: Vulnerability published April 2026; act now to prevent algorithm confusion attacks.