CVE-2026-40189
Unauthenticated ACL bypass in goshs <2.0.0-beta.4 allows file upload, delete, and dir creation.
Is CVE-2026-40189 being exploited?
Not confirmed. CVE-2026-40189 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 0.64% probability of exploitation in the next 30 days.
How severe is CVE-2026-40189?
CVE-2026-40189 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-2026-40189?
Yes. A fix has been recorded for CVE-2026-40189. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-40189 affect?
CVE-2026-40189 affects goshs (Go SimpleHTTPServer) <2.0.0-beta.4>. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-40189?
Upgrade to 2.0.0-beta.4 or newer.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attacker can upload files, create directories, delete content, bypassing per-folder ACLs and accessing protected data.
Immediate action required
- affected< 2.0.0-beta.4
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.