CVE-2026-21903
Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash
- State
- Published
- Severity
- 7.1 High
- Published
- Jan 15, 2026
- Updated
- Jan 15, 2026
- Reserved
- Jan 5, 2026
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 before 23.2R2-S4, * 23.4 versions before 23.4R2.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.1 High | 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 | juniper |
| 3.1 | 6.5 Medium | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | juniper |
Weaknesses
- CWE-121 Stack-based Buffer Overflow
Affected Products
| Product | Versions |
|---|---|
Junos OSJuniper Networks |
|
References
- https://supportportal.juniper.net/JSA106022vendor-advisory
- https://kb.juniper.net/JSA106022vendor-advisory
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