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CVE-2021-26829

Exploitation: active CVSS 5.4 MEDIUM

CVSS base score: 5.4 (Medium) CISA · v3.1

Score assigned by CISA's Vulnrichment program; the vendor's CVE record did not include one.

OpenPLC ScadaBR Cross-site Scripting Vulnerability

Vendor: OpenPLC   Product: ScadaBR

Description

OpenPLC ScadaBR contains a cross-site scripting vulnerability via system_settings.shtm.

Lifecycle Timeline

Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 262 points from 2021-12-11, tracked daily from 2026-09-09; earlier points are weekly, which dates a spike to within a week. Peak probability 48.3% on 2025-11-29.

Published Applicability

CVE List v5 (CNA container) 1 affected · 0 fixed · 0 not affected

Check whether a specific version is affected →

What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.

Research & News Coverage

No mentions found in monitored research blogs or news feeds.

Detection & Exploitation

Scan
none published
Exploit / Pen Test
none published
Network IDS/IPS
none published
Host / SIEM
none published

Blind spot. No public detection — verify by version/patch. Nothing in the monitored scanner, IDS, SIEM or offensive-tool collections references this CVE, so exposure has to be established from asset inventory and patch level rather than from a signature.

Coverage across public collections only: Nuclei and OpenVAS NVT (scan); Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM); Metasploit, Exploit-DB and public GitHub repositories (exploit). Absence here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by PoC-in-GitHub (CC0) and are not vetted: some are fakes and some are malware. Treat them as evidence that code was published, not as code to run.
OpenVAS coverage derives from the Greenbone Community Feed, made available under the Open Database License (ODbL) v1.0; its individual Vulnerability Tests are licensed GNU GPL v2.

CISA Assessment (Vulnrichment / SSVC)

active
no
partial
5.4 MEDIUM
—
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
2025-11-27

D3FEND Countermeasures

Defensive techniques inferred by MITRE D3FEND from the underlying weakness (CWE-79) — general hardening and detection guidance for this weakness class, not a vendor patch for this specific CVE.

KEV Catalog Status

2025-11-28
2025-12-19
Unknown

Listed By

SourceDateRecord
CISA Vulnrichment 2025-11-27 source record →
CISA KEV 2025-11-28 source record →

Weaponization Timeline — Offensive & Testing Tools

No exploit-tool sightings recorded for this CVE.

Evidence tiers are explained on the About page — a merged Metasploit module is far stronger evidence than a distro package mention.

External References