CVE-2026-73254— Mongoose: Stored XSS via unescaped filenames in directory listing
Quick assessment
Affected
cesanta mongoose
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Cesanta Mongoose是爱尔兰Cesanta公司开源的一个嵌入式Web服务器。 Cesanta Mongoose 7.22之前版本存在跨站脚本漏洞，该漏洞源于src/http.c中的printdirentry()函数在生成目录列表时未对文件名进行转义处理，将原始文件名插入HTML链接文本，导致存储型跨站脚本攻击，可能暴露会话数据或允许以受害者身份执行操作。
Possible ATT&CK Techniques 1 AI
T1189 · Drive-by Compromise
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I. Basic Information for CVE-2026-73254
Vulnerability Information
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Vulnerability Title
Mongoose: Stored XSS via unescaped filenames in directory listing
Source: CVE Program / CVE List V5
Vulnerability Description
Mongoose is an embedded web server and network library. Prior to 7.22, an attacker who can create a file with an HTML payload in its name can trigger stored cross-site scripting when a user browses a directory served with MG_ENABLE_DIRLIST. The printdirentry() path called by listdir() in src/http.c URL-encodes the href but inserts the raw filesystem filename into the HTML link text. The browser executes the injected markup in the Mongoose origin, which can expose session data or permit actions as the victim. This issue is fixed in version 7.22.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
Cesanta Mongoose 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Cesanta Mongoose是爱尔兰Cesanta公司开源的一个嵌入式Web服务器。 Cesanta Mongoose 7.22之前版本存在跨站脚本漏洞，该漏洞源于src/http.c中的printdirentry()函数在生成目录列表时未对文件名进行转义处理，将原始文件名插入HTML链接文本，导致存储型跨站脚本攻击，可能暴露会话数据或允许以受害者身份执行操作。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-73254
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Patches & Fixes for CVE-2026-73254 (1)
Vendor Advisories for CVE-2026-73254 (1)
Vendor Pages for CVE-2026-73254 (1)
Same Patch Batch · cesanta · 2026-08-20 · 8 CVEs total
| CVE-2026-73251 | 9.3 CRITICAL | Mongoose Built-in TLS: CA-bundle certificate chain accepted without any signature verifica |
| CVE-2026-73257 | 9.1 CRITICAL | Mongoose: Content-Length + Transfer-Encoding coexistence enables request smuggling |
| CVE-2026-73256 | 9.1 CRITICAL | Mongoose: HTTP/1.0 detection off-by-one enables request smuggling via chunked TE |
| CVE-2026-73253 | 9.1 CRITICAL | Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching |
| CVE-2026-73258 | 6.5 MEDIUM | Mongoose: Multipart boundary/header scan logic error in mg_http_next_multipart |
| CVE-2026-73255 | 6.5 MEDIUM | Mongoose: Path traversal in SSI #include directives enables arbitrary file read |
| CVE-2026-73259 | 5.4 MEDIUM | Mongoose: Reflected XSS via decoded URI in directory listing render |
IV. Related Vulnerabilities
Same product: mongoose
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CVE-2026-63626
Mongoose: ppp_handle_ipv6cp() uses attacker-controlled lengt -
CVE-2026-73261
Mongoose: handle_opt() missing opts[1] > len check — 1-byte -
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CVE-2026-73252
Mongoose: Unauthenticated remote heap out-of-bounds read in -
CVE-2026-101003
Cesanta Mongoose MQTT Broker main.c fn stack-based overflow
Same vendor: cesanta
-
CVE-2026-63626
Mongoose: ppp_handle_ipv6cp() uses attacker-controlled lengt -
CVE-2026-73261
Mongoose: handle_opt() missing opts[1] > len check — 1-byte -
CVE-2026-73260
Mongoose: Out-of-bounds Read via length-counter underflow in -
CVE-2026-73252
Mongoose: Unauthenticated remote heap out-of-bounds read in -
CVE-2026-101003
Cesanta Mongoose MQTT Broker main.c fn stack-based overflow
Same weakness: CWE-79
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CVE-2026-69194
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CVE-2026-0316
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CVE-2026-54701
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