Is CVE-2026-21921 being actively exploited?

CVE-2026-21921 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2026-21921?

CVE-2026-21921 has a CVSS 3.1 base score of 6.5 (MEDIUM).

CVE-2026-21921

MEDIUM · CVSS 6.5EPSS 0.4%EU EUVD

A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS). When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered. This issue affects: Junos OS: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; Junos OS Evolved: * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-EVO.

Key facts

CVSS score: 6.5 (v3.1)
Severity: MEDIUM
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-416
EPSS score: 0.4% (29th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2026-2693)
Published: January 15, 2026
NVD last modified: June 17, 2026
Status: Analyzed

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2026-2693 in the EU Vulnerability Database. Last updated in EUVD on January 15, 2026.

View on the EU Vulnerability Database

Affected products

juniper / junos
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and 8 more…

Certified products that may be affected

5 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

Junos Space Network Management Platform, with or without Network Director and with or without Security Director in JA2500 - Juniper Networks, Inc. - FIPS 140 3816 - historical
Juniper Networks SRX345/SRX345-DUAL-AC with Junos 15.1X49-D110 - Juniper Networks, Inc. - FIPS 140 3247 - historical
Junos-FIPS 10.4 L2 OS Cryptographic Module - Juniper Networks, Inc. - FIPS 140 1813 - historical
Junos-FIPS 10.4 L1 OS Cryptographic Module - Juniper Networks, Inc. - FIPS 140 1772 - historical
JUNOS-FIPS - Juniper Networks, Inc. - FIPS 140 602 - historical

References

https://kb.juniper.net/JSA106021(Vendor Advisory)
https://supportportal.juniper.net/JSA106021(Vendor Advisory)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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