Unchecked Return Value Vulnerability in Juniper Networks Junos OS on SRX Series
CVE-2026-21920

8.7HIGH

Key Information:

Vendor

Juniper Networks
Status
Junos Os
Vendor
CVE Published:
15 January 2026

Badges

👾 Exploit Exists

What is CVE-2026-21920?

A vulnerability exists in the DNS module of Juniper Networks' Junos OS on SRX Series devices, whereby an unauthenticated, network-based attacker can exploit this issue to induce a Denial-of-Service (DoS) condition. When a specifically formatted DNS request is received by an SRX Series device configured for DNS processing, the flowd process will crash and subsequently restart, leading to a service interruption that persists until the process stabilizes. It is crucial to note that this vulnerability impacts specific versions of Junos OS on SRX Series devices, while earlier versions remain unaffected.

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Affected Version(s)

Junos OS SRX Series 23.4 < 23.4R2-S5

Junos OS SRX Series 24.2 < 24.2R2-S1

Junos OS SRX Series 24.4 < 24.4R2

References

https://supportportal.juniper.net/JSA106020
vendor-advisory
https://kb.juniper.net/JSA106020
vendor-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

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