Affects Juniper MX Series core routers (SPC3); can cause network-wide DoS and reboot of infrastructure used by carriers and enterprises.
CVE-2026-102077
Malformed IPv6 causes NAT session exhaustion on Juniper MX (SPC3), leading to device-wide DoS.
Is CVE-2026-102077 being exploited?
Not confirmed. CVE-2026-102077 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 0.34% probability of exploitation in the next 30 days.
How severe is CVE-2026-102077?
CVE-2026-102077 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-2026-102077?
Yes. A fix has been recorded for CVE-2026-102077. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-102077 affect?
CVE-2026-102077 affects Juniper Junos OS on MX Series with SPC3, All versions before 23.2R2-S4, 23.4 versions before 23.4R2-S5, 24.2 versions before 24.2R2. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-102077?
Upgrade to vendor fixed Junos releases; block/inspect IPv6 at edge and monitor session/nat usage.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote, unauthenticated network DoS: malformed IPv6 packets create NAT sessions, exhaust resources and require reboot.
Immediate action required
- affected< 23.2R2-S4
- affected>= 23.4 and < 23.4R2-S5
- affected>= 24.2 and < 24.2R2
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.