Connect your agent
AdvisoriesCriticalCheck your lockfilePluginHow it worksPricing Connect your agent

CVE record · CVE-2026-21909

Junos OS and Junos OS Evolved: Receipt of specific IS-IS update packet causes memory leak leading to RPD crash

CVSS 7.1 HighEPSS 0.0025 · 16th percentile

Published by the CVE Program (CNA: juniper) at 15 Jan 2026, 20:22 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
VendorProductVersions
Juniper Networks Junos OS
  • affected 23.2 to before 23.2R2 semver
  • affected 23.4 to before 23.4R1-S2, 23.4R2 semver
  • affected 24.1 to before 24.1R2 semver
  • unaffected before 23.2R1 semver
Other versions: unaffected
Juniper Networks Junos OS Evolved
  • affected 23.2 to before 23.2R2-EVO semver
  • affected 23.4 to before 23.4R1-S2-EVO, 23.4R2-EVO semver
  • affected 24.1 to before 24.1R2-EVO semver
  • unaffected before 23.2R1-EVO semver
Other versions: unaffected
Identifiers
CVE-2026-21909
CNA
juniper
Weakness (CWE)
CWE-401
Tags
Published
15 Jan 2026
Updated
15 Jan 2026

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.5 Medium 3.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CNA (juniper)
7.1 High 4.0 CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Green CNA (juniper)Used for this record
  • CISA KEV Not listed.
  • EPSS 0.0025, the 16th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 15 Jan 2026. New records show when each source confirmed them.

Sources

References from the CNA

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.