2026-04 Security Bulletin: Junos OS: MX Series: In specific DHCPv6 scenarios jdhcpd memory increases continuously with subscriber logouts (CVE-2026-33782)

Product Affected

This issue affects all versions of Junos OS. Affected platforms: MX Series.

Severity

Medium

Severity Assessment (CVSS) Score

CVSS: v3.1: 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVSS: v4.0: 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/RE:M)

Problem

A Missing Release of Memory after Effective Lifetime vulnerability in the DHCP daemon (jdhcpd) of Juniper Networks Junos OS on MX Series, allows an adjacent, unauthenticated attacker to cause a memory leak, that will eventually cause a complete Denial-of-Service (DoS).

In a DHCPv6 over PPPoE, or DHCPv6 over VLAN with Active lease query or Bulk lease query scenario, every subscriber logout will leak a small amount of memory. When all available memory has been exhausted, jdhcpd will crash and restart which causes a complete service impact until the process has recovered.

The memory usage of jdhcpd can be monitored with:

user@host> show system processes extensive | match jdhcpd

This issue affects Junos OS:

all versions before 22.4R3-S1,
23.2 versions before 23.2R2,
23.4 versions before 23.4R2.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

Solution

The following software releases have been updated to resolve this specific issue: 22.4R3-S1, 23.2R2, 23.4R2, 24.2R1, and all subsequent releases.

This issue is being tracked as 1777055 which is visible on the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Workaround

There are no known workarounds for this issue.

Severity Assessment

Information for how Juniper Networks uses CVSS can be found at KB 16446 [juniper.net] "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Modification History