CVE-2026-21913
Unauthenticated DoS on Juniper EX4000 via IDM, network-based.
Is CVE-2026-21913 being exploited?
Not confirmed. CVE-2026-21913 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.41% probability of exploitation in the next 30 days.
How severe is CVE-2026-21913?
CVE-2026-21913 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-21913?
Yes. A fix has been recorded for CVE-2026-21913. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-21913 affect?
CVE-2026-21913 affects Juniper Networks Junos OS EX4000-48T, Juniper Networks Junos OS EX4000-48P, Juniper Networks Junos OS EX4000-48MP. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-21913?
Upgrade to fixed versions: 24.4R2 or 25.2R1-S2/25.2R2
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
DoS via high traffic causing FXPC crash and reboot, leading to outage of affected devices.
Immediate action required
- affected>= 24.4 and < 24.4R2
- affected>= 25.2 and < 25.2R1-S2, 25.2R2
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.