CVE-2026-73253
Hostname verification bypass in Mongoose TLS allows wildcard cert MITM.
Is CVE-2026-73253 being exploited?
Not confirmed. CVE-2026-73253 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 0.21% probability of exploitation in the next 30 days.
How severe is CVE-2026-73253?
CVE-2026-73253 is rated Critical. 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-2026-73253?
Yes. A fix has been recorded for CVE-2026-73253. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-73253 affect?
CVE-2026-73253 affects Mongoose (embedded web server) versions < 7.22 with built-in TLS, Devices and applications embedding Mongoose TLS stack. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-73253?
Upgrade to Mongoose 7.22+ or disable built-in TLS; enforce strict hostname verification.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
On-path attacker with a wildcard parent-domain cert can bypass hostname checks, enabling TLS MITM to intercept/modify traffic.
Immediate action required
- affected< 7.22
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.