CVE-2021-33023
No exploitation reported by the sources we read.
- Published2021-10-18
- WeaknessCWE-122 · CWE-787
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
Advantech WebAccess versions 9.02 and prior are vulnerable to a heap-based buffer overflow, which may allow an attacker to remotely execute code.
Timeline
dates in UTC- 2021-10-1813:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-33023?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-33023?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 9.0 | ≤ 9.0.2 | no fix published | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
Advantech WebAccess
WebAccess: Versions 9.02 and prior
Fix
- Vendor fix CISA ICSA-21-285-02 · 1 productIn order to address the heap-based buffer overflow vulnerability, Advantech recommends users directly add the remote access code to avoid being attacked by unknown requests. This is the remote access code established during installation of the Advantech WebAccess SCADA software (SCADA node, project…
- Vendor fix CISA ICSA-21-285-02 · 1 productRe-install the Advantech WebAccess SCADA software on the OPC Server node to change it and edit it to match in your database.
- Mitigation from the vendor CISA ICSA-21-285-02 · 1 productAdvantech has released Version 9.1.1 to address the stack-based buffer overflow vulnerability.
- Mitigation from the vendor CISA ICSA-21-285-02 · 1 productIf you have forgotten the remote access code using during software installation on the OPC Server node, you have two options:
- Mitigation from the vendor CISA ICSA-21-285-02 · 1 productEdit the BWSERVER.INI file on the OPC Server node and edit it to match in your database using UPDATE.
Advisories and patches
- us-cert.cisa.govMitigation
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Published
- 2021-10-18
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-33023?
Is CVE-2021-33023 actively exploited?
What is the CVSS score for CVE-2021-33023?
Running Advantech WebAccess? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
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Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.