Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching (CVE-2026-73253) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-73253

Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching

Answer in brief

CVE-2026-73253 records a Unknown severity vulnerability in Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching. The current sources do not mark it as known exploited. The current feed maps cesanta/mongoose (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 20, 2026Updated Aug 20, 2026Source checked Aug 20, 2026First seen by HOL Aug 20, 2026Material review Aug 20, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps cesanta/mongoose (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
cesanta/mongoosegeneric	< 7.22	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for cesanta/mongoose.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 20, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 20, 2026

Sources and claim methodology

Upstream source description

Mongoose is an embedded web server and network library. Prior to version 7.22, an on-path network attacker with a wildcard certificate for a parent domain can impersonate deeper subdomains to a client using the built-in TLS stack. The mg_tls_verify_cert_san() and mg_tls_verify_cert_cn() functions in src/tls_builtin.c call mg_match(), whose wildcard can cross DNS label boundaries, so a pattern such as *.example.com can match foo.bar.example.com. The resulting hostname verification bypass permits interception and modification of TLS traffic. This issue is fixed in version 7.22.

Quoted source text, attributed separately from HOL analysis.