ZeusQA
Start free

Known exploited vulnerability

CVE-2021-26829

mediumCVSS 3.1 5.4In CISA KEVEPSS 48%Published · n/a

The short answer

CVE-2021-26829 affects n/a n/a and is rated medium (CVSS 5.4). CISA added it to the Known Exploited Vulnerabilities catalog on 2025-11-28: attackers are using it, so patch it first.

What it is

OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm.

Weakness: CWE-79.

Severity

5.4 medium

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Exploited (CISA KEV)

Yes, since Nov 28, 2025

Federal due date Dec 19, 2025

EPSS, next 30 days

48%

Higher than 99% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Changed
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Affected products

n/a. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2021-26829 being exploited?

Yes. CISA added CVE-2021-26829 to its Known Exploited Vulnerabilities catalog on 2025-11-28, with a federal remediation due date of 2025-12-19.

How do I fix CVE-2021-26829?

CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

Related

Know the day a CVE lands in your code

Connect a GitHub repository and ZeusQA checks its dependencies daily, briefs each advisory and opens the fix. Three test runs free, no card.

Start freeSee how a run works