CVE-2026-73254: Mongoose is an embedded web server and network library

Q: How do I fix CVE-2026-73254?

mongoose: upgrade to 7.22. Exact commands for each OS are on this page.

Q: Is CVE-2026-73254 being exploited?

CVE-2026-73254 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-2026-73254 affect?

CVE-2026-73254 affects mongoose. Severity is medium (CVSS 5.4). 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.

Q: How urgent is CVE-2026-73254?

Priority 31/100. Public exploit reference

Routine

MEDIUM 5.4UPGRADE

CVE-2026-73254 is a medium-severity flaw (CVSS 5.4) affecting mongoose. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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,

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 72%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-08-20
Last modified	2026-10-18

Publisher (CNA): GitHub, Inc. · Vendor: cesanta

Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-20 18:16 UTCPublished CVE record published
2026-10-18 20:10 UTCUpdated Record last modified

cesanta mongoose UPGRADE

Affected: < 7.22

Fixed in: 7.22

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 7.22 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mongoose

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-2026-73254?

mongoose: upgrade to 7.22. Exact commands for each OS are on this page.

Is CVE-2026-73254 being exploited?

CVE-2026-73254 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-2026-73254 affect?

CVE-2026-73254 affects mongoose. Severity is medium (CVSS 5.4). 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.

How urgent is CVE-2026-73254?

Priority 31/100. Public exploit reference

Related CVEs

CVE-2026-5244 HIGH 7.3 UPGRADE A vulnerability has been found in Cesanta Mongoose up to 7.20
CVE-2026-6985 MEDIUM 5.3 UPGRADE A weakness has been identified in Cesanta Mongoose up to 7.20
CVE-2026-5246 MEDIUM 5.6 UPGRADE A vulnerability was determined in Cesanta Mongoose up to 7.20
CVE-2026-5245 MEDIUM 5.6 UPGRADE A vulnerability was found in Cesanta Mongoose up to 7.20
CVE-2026-6986 LOW 3.7 UPGRADE A security vulnerability has been detected in Cesanta Mongoose up to 7.20

References

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