Affects Juniper Junos — core routing OS used across enterprises and service providers; can compromise routing-engine or cause network-wide outages.
CVE-2026-102178
Stack buffer overflow in Junos BGP flowspec enabling routing-engine compromise.
Is CVE-2026-102178 being exploited?
Not confirmed. CVE-2026-102178 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 0.45% probability of exploitation in the next 30 days.
How severe is CVE-2026-102178?
CVE-2026-102178 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-2026-102178?
Not known from our data. No patch reference has been recorded for CVE-2026-102178, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-102178 affect?
CVE-2026-102178 affects Juniper Junos OS, Juniper Junos OS Evolved, Junos BGP routing daemon (flowspec), Routing Engine. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-102178?
Apply Juniper advisory patches immediately; if unavailable, disable BGP flowspec peers or BGP update-threading.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution or routing-engine compromise and routing-daemon DoS via crafted BGP flowspec re-advert when BGP update-threading is enabled.
Immediate action required
- affected< 23.2R2-S7.7
- affected>= 23.4 and < 23.4R2-S8.13
- affected>= 24.2 and < 24.2R2-S5.5
- affected>= 24.4 and < 24.4R2-S5
- affected>= 25.2 and < 25.2R2-S2
- affected>= 25.4 and < 25.4R1-S3
- affected>= 26.2 and < 26.2R1-S2
- affected< 23.2R2-S7.7-EVO
- affected>= 23.4 and < 23.4R2-S8.11-EVO
- affected>= 24.2 and < 24.2R2-S5.6-EVO
- affected>= 24.4 and < 24.4R2-S5-EVO
- affected>= 25.2 and < 25.2R2-S2-EVO
- affected>= 25.4 and < 25.4R1-S3-EVO
- affected>= 26.2 and < 26.2R1-S2-EVO
- affected23.4X100
- affected>= 25.2X100 and < 25.2X100-D35-EVO
- affected>= 25.4X300 and < 25.4X300-D40-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.