CVE-2026-73257
Unauthenticated HTTP request-smuggling in Mongoose allows injected requests.
Is CVE-2026-73257 being exploited?
Not confirmed. CVE-2026-73257 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 0.48% probability of exploitation in the next 30 days.
How severe is CVE-2026-73257?
CVE-2026-73257 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-2026-73257?
Yes. A fix has been recorded for CVE-2026-73257. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-73257 affect?
CVE-2026-73257 affects Mongoose < 7.22, Applications and devices embedding Mongoose (IoT/embedded systems). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-73257?
Upgrade to Mongoose 7.22+ and review reverse-proxy header handling.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote unauthenticated CL+TE request-smuggling lets attackers inject requests to access/modify other users' resources and impersonate sessions.
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.