CVE-2021-36603: Cross Site Scripting (XSS) in Tasmota firmware 6.5.0 allows remote attackers to inject JavaScript code via a c

Routine

MEDIUM 6.1MITIGATE

CVE-2021-36603 is a medium-severity flaw (CVSS 6.1) affecting tasmota. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross Site Scripting (XSS) in Tasmota firmware 6.5.0 allows remote attackers to inject JavaScript code via a crafted string in the field "Friendly Name 1".

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 57%)
CISA exploited list	No
Weakness	CWE-79
Published	2023-01-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: tasmota project

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

Am I affected?

Timeline

2023-01-09 21:15 UTCPublished CVE record published
2026-06-17 03:58 UTCUpdated Record last modified

tasmota project tasmota MITIGATE

Affected: 6.5.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.5.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-36603?

tasmota: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-36603 being exploited?

CVE-2021-36603 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-2021-36603 affect?

CVE-2021-36603 affects tasmota. Severity is medium (CVSS 6.1). Cross Site Scripting (XSS) in Tasmota firmware 6.5.0 allows remote attackers to inject JavaScript code via a crafted string in the field "Friendly Name 1".

How urgent is CVE-2021-36603?

Priority 37/100. Public exploit reference

Related CVEs

CVE-2022-43294 CRITICAL 9.8 UPGRADE Tasmota before commit 066878da4d4762a9b6cb169fdf353e804d735cfd was discovered to contain a stack overflow via

References

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