CVE-2026-73254

Mongoose: Stored XSS via unescaped filenames in directory listing

MEDIUM
5.4
CVSS Score
Published: August 20, 2026 at 05:37 PM UTC
Updated: October 18, 2026 at 08:10 PM UTC
1 product affected across 1 vendorMongoose

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Severity
MEDIUM5.4
Exploit prediction
EPSS 0.3%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 7.22
Affected range stops below 7.22, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/cesanta/mongoose/security/advisories/GHSA-5g6j-m3pv-4f7g
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/cesanta/mongoose/pull/3611
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/cesanta/mongoose/releases/tag/7.22

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.4MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79

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