CVE-2026-21903

mediumpriority · track · 0EPSS 0.004 · 34 %ileDEEUNLUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.40% (34th) EPSS

CVSS 6.5 · medium

Is it mine?

13 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · cert_bund · ncsc_nl

EPSS · scored 2026-10-27

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

Technical severity, 0–10. One row per scoring source.

7.1

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.9–7.1

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hsecondary · sirt@juniper.net USexploitability 2.8 · impact 3.6

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hsecondary · NCSC-NL NL

v4.07.1highCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:Lsecondary · ENISA EU

v4.07.1highCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · sirt@juniper.net US

v4.04.9mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-121USCWE-121US

affected products (13)

Products and version ranges known to be affected.

Juniper JUNOS OSall versionscert_bundDEcpe:/o:juniper:junos:os
Juniper Networks Junos OS0 → 22.4R3-S7enisa_euvdEU
Juniper Networks Junos OS23.2 → 23.2R2-S4enisa_euvdEU
Juniper Networks Junos OS23.4 → 23.4R2enisa_euvdEU
Juniper Networks Junos OS≤ vers:unknown/*ncsc_nlNL
Juniper Networks Junos OS Evolved≤ vers:unknown/*ncsc_nlNL
Juniper Networks Junos Space≤ vers:unknown/*ncsc_nlNL
Juniper Networks Paragon Automation (Pathfinder, Planner, Insights)≤ vers:unknown/*ncsc_nlNL
Juniper Networks Spac≤ vers:unknown/*ncsc_nlNL
juniper junos< 22.4nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos= 22.4nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos= 23.2nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos= 23.4nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*

advisories (2)

Vendor and ecosystem advisories describing this.

NCSC-2026-0017Kwetsbaarheden verholpen in Juniper Networks JunOSNL2026-01-16csaf · ncsc_nlNL
Juniper heeft kwetsbaarheden verholpen in Junos OS (Specifiek voor SRX en MX Series apparaten).
WID-SEC-W-2026-0117Juniper Junos OS, Junos Space: Mehrere SchwachstellenDeutsch2026-01-14csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Juniper JUNOS und Juniper Junos Space ausnutzen, um falsche Informationen darzustellen, beliebigen Code mit Root-Rechten auszuführen, Daten zu manipulieren, vertrauliche Informationen offenzulegen und einen Denial-of-Service-Zustand zu verursachen.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund ncsc_nl nvd NVD CVE.org MITRE

published 2026-01-15modified 2026-06-17

references (7)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan