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NVD / CVE Program· CNA mitre

CVE-2021-26829: OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm.

MediumCVSS 5.4 · v3.1KEVWeaponized No fix recorded

Noroxi assessment

Priority: This week (action score 65/100)

  • CISA has confirmed exploitation in the wild (Nov 28, 2025). Remediation deadline for US federal agencies: Dec 19, 2025.
  • Probability of exploitation in the next 30 days: 48% (FIRST EPSS); higher than 98.8% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Don’t wait for the next maintenance window. Until a fix is released, restrict access to the affected component and follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

Published
Jun 11, 2021
Updated
Jun 16, 2026
EPSS
48.0% · 98th percentile

Report tools

JSON

Action score

65

This week

Don’t wait for the next maintenance window.

CVSS
21 / 40 · 5.4 / 10
CISA KEV
30 / 30 · Listed
EPSS
14 / 30 · 48.0%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Nov 28, 2025. That signals real attacks, not theory.

Remediation deadline for US federal agencies: Dec 19, 2025.

Get told when this record changes

  • In CISA KEV: exploitation in the wild confirmed
  • Weaponized exploit exists
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-26829

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
scadabrscadabr
linuxlinux kernel
microsoftwindows

Limit the impact of XSS

This is a cross-site scripting (XSS) vulnerability. A well-configured Content-Security-Policy doesn't fix it, but greatly reduces its impact. Check your site's CSP and other security headers for free.

Check security headers

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • scadabr scadabrup to 0.9.1 inclusive
  • scadabr scadabrup to 1.12.4 inclusive

Same product

scadabr: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-26828OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows remote authenticated users to upload and execute arbitrary JSP…KEV
    77This week
  • CVE-2026-9645ScadaBR Authenticated Remote Code Execution
    39Monitor
  • CVE-2026-8602Missing authentication for critical function in ScadaBR
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2019-16321Sep 15, 2019 · ScadaBR 1.0CE, and 1.1.x through 1.1.0-RC, has XSS via a request for a nonexistent resource, as demonstrated by the dwr/test/ PATH_INFO.
    24Monitor
  • ← EarlierCVE-2019-16344Oct 14, 2019 · A cross-site scripting (XSS) vulnerability in the login form (/ScadaBR/login.htm) in ScadaBR 1.0CE allows a remote attacker to inject…
    24Monitor
  • Later →CVE-2025-70973Mar 9, 2026 · ScadaBR 1.12.4 is vulnerable to Session Fixation.
    19Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. CISA KEV+1631 d
  3. TodayNov 14, 2026+1982 d

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

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

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

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

nvd-primary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records