CVE-2026-21909
Severity CVSS v4.0:
HIGH
Type:
Unavailable / Other
Publication date:
15/01/2026
Last modified:
15/01/2026
Description
A Missing Release of Memory after Effective Lifetime vulnerability in the routing protocol daemon (rpd) Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated attacker controlling an adjacent IS-IS neighbor to send a specific update packet causing a memory leak. Continued receipt and processing of these packets will exhaust all available memory, crashing rpd and creating a Denial of Service (DoS) condition.<br />
<br />
Memory usage can be monitored through the use of the &#39;show task memory detail&#39; command. For example:<br />
<br />
user@junos> show task memory detail | match ted-infra<br />
TED-INFRA-COOKIE 25 1072 28 1184 229<br />
<br />
<br />
<br />
user@junos> <br />
<br />
show task memory detail | match ted-infra<br />
TED-INFRA-COOKIE 31 1360 34 1472 307<br />
<br />
This issue affects:<br />
<br />
Junos OS: <br />
<br />
* from 23.2 before 23.2R2, <br />
* from 23.4 before 23.4R1-S2, 23.4R2, <br />
* from 24.1 before 24.1R2; <br />
<br />
<br />
Junos OS Evolved: <br />
<br />
* from 23.2 before 23.2R2-EVO, <br />
* from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO, <br />
* from 24.1 before 24.1R2-EVO.<br />
<br />
<br />
This issue does not affect Junos OS versions before 23.2R1 or Junos OS Evolved versions before 23.2R1-EVO.
Impact
Base Score 4.0
7.10
Severity 4.0
HIGH
Base Score 3.x
6.50
Severity 3.x
MEDIUM