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Medium severity6.5NVD Advisory· Published Jan 15, 2026· Updated Jun 17, 2026

CVE-2026-21903

CVE-2026-21903

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.

Affected products

29
  • Juniper Networks/Junos29 versions
    cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*+ 28 more
    • cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*range: <22.4
    • cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s5:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s6:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
    • (no CPE)range: <22.4R3-S7, <23.2R2-S4, <23.4R2
    • (no CPE)range: 0

Patches

Vulnerability mechanics

References

2

News mentions

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