Affects core network infrastructure; unauthenticated RCE on Junos PTX devices could disrupt operations across organizations.
CVE-2026-21902
Unauthenticated remote code execution on Junos OS Evolved PTX.
Is CVE-2026-21902 being exploited?
Not confirmed. CVE-2026-21902 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 18% probability of exploitation in the next 30 days.
How severe is CVE-2026-21902?
CVE-2026-21902 is rated Critical with a CVSS score of 9.3. 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-2026-21902?
Yes. A fix has been recorded for CVE-2026-21902. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-21902 affect?
CVE-2026-21902 affects Juniper Junos OS Evolved on PTX Series (25.4 before 25.4R1-S1-EVO, 25.4R2-EVO). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-21902?
Upgrade to 25.4R1-S1-EVO or 25.4R2-EVO
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can run code as root on affected PTX devices via exposed port; full device takeover possible.
Immediate action required
- affected>= 25.4 and < 25.4R1-S1-EVO, 25.4R2-EVO
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.