CVE-2020-13697: An issue was discovered in RouterNanoHTTPD.java in NanoHTTPD through 2.3.1

Q: How do I fix CVE-2020-13697?

nanohttpd: upgrade to newer than 2.3.1. Exact commands for each OS are on this page.

Q: Is CVE-2020-13697 being exploited?

CVE-2020-13697 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-13697 affect?

CVE-2020-13697 affects nanohttpd. Severity is medium (CVSS 6.1). 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 i

Q: How urgent is CVE-2020-13697?

Priority 35/100. No elevated risk signals yet.

Routine

MEDIUM 6.1UPGRADE

CVE-2020-13697 is a medium-severity flaw (CVSS 6.1) affecting nanohttpd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-02-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: nanohttpd

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-02-23 08:15 UTCPublished CVE record published
2026-06-17 02:53 UTCUpdated Record last modified

nanohttpd nanohttpd UPGRADE

Affected: <= 2.3.1

Fixed in: newer than 2.3.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nanohttpd || rpm -q nanohttpd || nanohttpd --version

2. UPGRADE to newer than 2.3.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nanohttpd

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nanohttpd

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-13697?

nanohttpd: upgrade to newer than 2.3.1. Exact commands for each OS are on this page.

Is CVE-2020-13697 being exploited?

CVE-2020-13697 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-13697 affect?

CVE-2020-13697 affects nanohttpd. Severity is medium (CVSS 6.1). 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 i

How urgent is CVE-2020-13697?

Priority 35/100. No elevated risk signals yet.

Software pages

Java vulnerabilities

Related CVEs

CVE-2022-21230 MEDIUM 5.5 UPGRADE This affects all versions of package org.nanohttpd:nanohttpd

References

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