Maverc
All articlesVulnerabilities

Juniper Networks Addresses Critical Vulnerabilities in SRX Firewalls and EX Switches (CVE-2024-21591)

May 31, 20245 min readMaverc Threat Research · Threat Advisory
VulnerabilitiesRansomwareNetwork Security
Juniper Networks Addresses Critical Vulnerabilities in SRX Firewalls and EX Switches (CVE-2024-21591)

A critical RCE in Juniper SRX and EX devices (CVSS 9.8) lets unauthenticated attackers execute remote code via J-Web. Patch now.

Juniper Networks has addressed critical vulnerabilities in its SRX Series firewalls and EX Series switches. The most noteworthy is CVE-2024-21591, an out-of-bounds write remote code execution flaw with a CVSS score of 9.8. This vulnerability allows unauthenticated attackers with network access to the J-Web management interface to execute arbitrary code or trigger a denial-of-service condition.

Affected Versions

Junos OS releases prior to specific fixed builds across the 20.4R3, 21.2R3, 21.3R3, 21.4R3, 22.1R3, 22.2R3, 22.3R3, and 22.4R2 families. Consult the Juniper advisory for exact fix versions.

Immediate Actions

  • Patch to a fixed Junos OS release.
  • Restrict J-Web access to trusted management networks only — never expose it to the internet.
  • Disable J-Web entirely if it is not in use.
  • Audit logs for unexpected J-Web activity from unknown sources.

This is exactly the kind of edge appliance flaw that drives initial access for ransomware crews. Treat the patch with the same urgency as a perimeter VPN CVE.

Keep reading

Beyond MFA: Why Adversary-in-the-Middle Phishing Is Eating Your Identity Stack
Identity Security

Beyond MFA: Why Adversary-in-the-Middle Phishing Is Eating Your Identity Stack

Push-based MFA was a decade-old patch on a broken model. Here's how AiTM toolkits like EvilProxy and Tycoon 2FA defeat it — and the phishing-resistant controls that actually stop them.

The CMMC Level 2 Readiness Checklist We Wish Every DIB Contractor Had
Compliance

The CMMC Level 2 Readiness Checklist We Wish Every DIB Contractor Had

If you handle CUI, the C3PAO assessment is coming. Here's the 10-step readiness path Maverc walks every defense industrial base client through before the auditor shows up.

What a Modern OT Ransomware Attack Looks Like — And How to Survive One
OT / ICS Security

What a Modern OT Ransomware Attack Looks Like — And How to Survive One

From IT pivot to PLC shutdown, today's OT ransomware crews follow a repeatable playbook. Here is what we see in the field and the segmentation controls that contain the blast.