CVE-2026-21903: high-severity vulnerability in Juniper Networks Junos OS
Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.1epss 0.4%
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L
Affected products
Juniper Networks · Junos OSRelated CVEs — Juniper Networks Junos OS
In the same product, most dangerous first.
CVE-2023-36845CRITICALJunos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variableEPSS 95.1%KEVCVE-2023-36846MEDIUMJunos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesEPSS 93.5%KEVCVE-2023-36844MEDIUMJunos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variablesEPSS 90.0%KEVCVE-2023-36847MEDIUMJunos OS: EX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesEPSS 83.5%KEVCVE-2020-1631HIGHOut of Cycle Security Advisory: Junos OS: Security vulnerability in J-Web and web based (HTTP/HTTPS) servicesEPSS 4.9%KEVCVE-2025-21590MEDIUMJunos OS: An local attacker with shell access can execute arbitrary codeEPSS 1.7%KEV