NanoHTTPD Cross-site Scripting vulnerability

published 2021-02-23 5 y ago modified 2026-06-17 4 mo ago also GHSA-pr5m-4w22-8483 , EUVD-2021-0564

cvss: 6.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.8%; EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits: 0; none known

An issue was discovered in RouterNanoHTTPD.java in NanoHTTPD through 2.3.1. The GeneralHandler class implements a basic GET handler that prints debug information as an HTML page. Any web server that extends this class without implementing its own GET handler is vulnerable to reflected XSS, because the GeneralHandler GET handler prints user input passed through the query string without any sanitization.

Exploit prediction

0.76% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected packages

ecosystem	package	affected	fixed in
maven	org.nanohttpd:nanohttpd-nanolets	<=2.3.1	no fix listed

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /NanoHttpd/nanohttpd
package, product, third-party-advisory
vdoo.com /advisories
third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2020-13697
advisory
github.com /NanoHttpd/nanohttpd/blob/efb2ebf85a2b06f7c508aba9eaad5377e3a01e81/nanolets/pom.xml
web
github.com /NanoHttpd/nanohttpd/blob/efb2ebf85a2b06f7c508aba9eaad5377e3a01e81/nanolets/src/main/java/org/nanohttpd/router
web
vdoo.com /advisories/#CVE-2020-13697
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary