CVE-2026-73256
Mongoose HTTP/1.0 proxy parsing bug enables request smuggling and unauthorized access.
Is CVE-2026-73256 being exploited?
Not confirmed. CVE-2026-73256 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 0.40% probability of exploitation in the next 30 days.
How severe is CVE-2026-73256?
CVE-2026-73256 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-2026-73256?
Yes. A fix has been recorded for CVE-2026-73256. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-73256 affect?
CVE-2026-73256 affects Mongoose < 7.22, Embedded devices/appliances using Mongoose, HTTP/1.0 reverse-proxy deployments. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-73256?
Upgrade to Mongoose 7.22+; block/validate chunked Transfer-Encoding at proxies.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote unauthenticated attacker can perform HTTP request smuggling via crafted Transfer-Encoding: chunked, bypass proxies, gain unauthorized access or change state.
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.