Is CVE-2026-21903 being actively exploited?

CVE-2026-21903 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2026-21903?

CVE-2026-21903 has a CVSS 3.1 base score of 6.5 (MEDIUM).

CVE-2026-21903

MEDIUM · CVSS 6.5EPSS 0.4%EU EUVD

A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authenticated with low privileges to cause a Denial-of-Service (DoS). Subscribing to telemetry sensors at scale causes all FPC connections to drop, resulting in an FPC crash and restart. The issue was not seen when YANG packages for the specific sensors were installed. This issue affects Junos OS: * all versions before 22.4R3-S7, * 23.2 version before 23.2R2-S4, * 23.4 versions before 23.4R2.

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-121
EPSS score: 0.4% (32th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2026-2692)
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-2026-2692 in the EU Vulnerability Database. Last updated in EUVD on January 15, 2026.

View on the EU Vulnerability Database

Affected products

juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos
juniper / junos

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/JSA106022(Vendor Advisory)
https://supportportal.juniper.net/JSA106022(Vendor Advisory)

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

Query CVEs from your AI assistant

The CVE/NVD Explorer brain answers CVE questions directly inside Claude, ChatGPT, or any MCP assistant — always up to date, no setup. Add it once and stop pasting advisories into chat.

Add the CVE brain