CVE-2026-73259: medium-severity vulnerability in cesanta mongoose
Mongoose: Reflected XSS via decoded URI in directory listing render
Published
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.4epss 0.4%
Mongoose is an embedded web server and network library. Prior to 7.22, a remote attacker can send a crafted percent-encoded request path to a deployment using MG_ENABLE_DIRLIST and persuade a user to visit it. The mg_http_serve_dir() and listdir() path in src/http.c places the decoded request URI into the title and h1 elements without HTML entity encoding. The resulting reflected cross-site scripting executes in the Mongoose origin and can expose session data or perform actions as the victim. This issue is fixed in version 7.22.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Affected products
cesanta · mongooseRelated CVEs — cesanta mongoose
In the same product, most dangerous first.
CVE-2026-73257CRITICALMongoose: Content-Length + Transfer-Encoding coexistence enables request smugglingEPSS 0.7%CVE-2026-73255MEDIUMMongoose: Path traversal in SSI #include directives enables arbitrary file readEPSS 0.7%CVE-2026-73258MEDIUMMongoose: Multipart boundary/header scan logic error in mg_http_next_multipartEPSS 0.5%CVE-2026-73256CRITICALMongoose: HTTP/1.0 detection off-by-one enables request smuggling via chunked TEEPSS 0.4%CVE-2026-73261HIGHMongoose: handle_opt() missing opts[1] > len check — 1-byte OOB read corrupts TCP MSS, silences mg_send() per connectionEPSS 0.4%CVE-2026-73252HIGHMongoose: Unauthenticated remote heap out-of-bounds read in built-in TLS: off-by-one length check in mg_tls_recv_record() underflows recv_len to SIZE_MAXEPSS 0.4%