CVE-2026-55604
Session ID reuse flaw lets attackers hijack chat sessions and read/continue victim conversations.
Is CVE-2026-55604 being exploited?
Not confirmed. CVE-2026-55604 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 0.37% probability of exploitation in the next 30 days.
How severe is CVE-2026-55604?
CVE-2026-55604 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-2026-55604?
Yes. A fix has been recorded for CVE-2026-55604. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55604 affect?
CVE-2026-55604 affects DeepSeek MCP Server >=1.4.2 and <1.7.0, DeepSeek V4 deployments using MCP Server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55604?
Upgrade to DeepSeek MCP Server 1.7.0+, invalidate existing sessions, audit logs
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attackers can enumerate session_ids, reuse them to retrieve and continue victims' chat context, enabling data disclosure and user impersonation.
Immediate action required
- affected>= 1.4.2 and < 1.7.0
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.