CVE-2026-19874
Heap buffer overflow in Metal Gear Online 3 lobby parsing enables code execution.
Is CVE-2026-19874 being exploited?
Not confirmed. CVE-2026-19874 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 0.73% probability of exploitation in the next 30 days.
How severe is CVE-2026-19874?
CVE-2026-19874 is rated Critical with a CVSS score of 9.1. 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-2026-19874?
Not known from our data. No patch reference has been recorded for CVE-2026-19874, 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-2026-19874 affect?
CVE-2026-19874 affects Konami Metal Gear Online 3 (game client), Game process using Steam callback handlers. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-19874?
Apply vendor patch immediately when released; avoid untrusted lobbies and isolate/monitor game clients.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Crafted lobby data with oversized "kick_num" can overflow buffers and overwrite Steam callback structs, enabling arbitrary code execution in the game process.
Immediate action required
- affected1.1.2.8
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.