CVE-2026-21903

CWE-121 — Stack-based Buffer Overflow4 documents4 sources
Severity
7.1HIGH
EPSS
0.0%
top 95.29%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Juniper Networks Junos OSJuniper Junos
Timeline
PublishedJan 15

Description

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 bef…

CVSS vector

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 Packages2 packages

▶CVEListV5juniper_networks/junos_os23.2 — 23.2R2-S4+2
▶NVDjuniper/junos< 22.4+3

🔴Vulnerability Details

2
GHSA
GHSA-h3c8-3472-7v7g: A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authen↗2026-01-15
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CVEList
Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash↗2026-01-15
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📋Vendor Advisories

1
Juniper
CVE-2026-21903: A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authen↗2026-01-15
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CVE-2026-21903 (HIGH CVSS 7.1) | A Stack-based Buffer Overflow vulne | cvebase.io