CVE-2026-1773
ICS DoS via invalid U-format frames in IEC 60870-5-104 (bidirectional)
Is CVE-2026-1773 being exploited?
Not confirmed. CVE-2026-1773 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-2026-1773?
CVE-2026-1773 is rated High. 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-2026-1773?
Yes. A fix has been recorded for CVE-2026-1773. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-1773 affect?
CVE-2026-1773 affects IEC 60870-5-104 bidirectional implementations (ICS/SCADA). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-1773?
Monitor traffic; enable IEC 62351 to mitigate risk
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Denial of service on ICS/SCADA devices via crafted invalid U-format frames; bidirectional operation affected; IEC 62351 mitigates risk but does not patch.
Monitor only
- affected>= 12.7.1 and <= 12.7.7
- affected>= 13.5.1 and <= 13.5.4
- affected>= 13.6.1 and <= 13.6.2
- affected>= 13.7.1 and <= 13.7.7
- affected13.8.1
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.