PT-2026-3131 · Juniper Networks · Junos Srx Series

Published 2026-01-15 · Updated 2026-01-16 · CVE-2026-21920

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Juniper Networks Junos OS on SRX Series versions 23.4 before 23.4R2-S5 Juniper Networks Junos OS on SRX Series versions 24.2 before 24.2R2-S1 Juniper Networks Junos OS on SRX Series versions 24.4 before 24.4R2

Description An unchecked return value issue exists in the DNS module of Junos OS on SRX Series devices. An unauthenticated, network-based attacker can exploit this to cause a Denial-of-Service (DoS). Specifically, when an SRX Series device configured for DNS processing receives a specially crafted DNS request, the flowd process crashes and restarts, leading to a service interruption until the process recovers.

Recommendations Update Junos OS on SRX Series to version 23.4R2-S5 or later. Update Junos OS on SRX Series to version 24.2R2-S1 or later. Update Junos OS on SRX Series to version 24.4R2 or later.

Fix

Unchecked Return Value

Weakness Enumeration

CWE-252

Related Identifiers

CVE-2026-21920

Affected Products

Junos Srx Series

References · 6

• https://supportportal.juniper.net/JSA106020 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-21920 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21920 · Security Note
• https://kb.juniper.net/JSA106020 · Vendor Advisory
• https://twitter.com/CVEnew/status/2011926035328356721 · Twitter Post
• https://twitter.com/vuldb/status/2012088833467376081 · Twitter Post