CVE-2021-31630

Command Injection in Open PLC Webserver v3 allows remote attackers to execute arbitrary code via the "Hardware Layer Code Box" component on the "/hardware" page of the application.

CVSS: 8.8High
Exploited in the wild: Not knownUnvetted proof-of-concept code on GitHub; not in CISA KEV
EPSS: 27.1%chance of exploitation in the next 30 daystop 2% of scored CVEsFIRST score of 11 Nov 2026
Fix: Not stated by the vendorno fixed release in the CVE record
Published: 3 Aug 2021analysed here 12 Nov 2026

Summary

Triage

Attack surface: Server-side
Exploitable: At runtime
Attack vector: network
Weakness: CWE-94 Code Injection
Can a WAF block it?: Partly. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

openplcproject:openplc_v3_firmware

Fix and mitigation

WAF and other mitigations

Can a WAF block it? Partly. Code injection payloads are often obfuscated, so they slip past generic WAF rules.

Also consider: remove eval sinks · RASP

Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Not listed as of our last sync.
Public exploit code: Unvetted proof-of-concept code on GitHub: 12 GitHub proofs of concept

GitHub proofs of concept

thewhiteh4t/cve-2021-3163022 stars
Hunt3r0x/CVE-2021-31630-HTB9 stars
machevalia/OpenPLC-CVE-2021-31630-RCE3 stars
hev0x/CVE-2021-31630-OpenPLC_RCE2 stars

and 8 more repositories

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

2 Aug 2021First proof-of-concept repository on GitHub (unvetted)
3 Aug 2021Published2 days later
3 Aug 2024CVE record last updated1,096 days (about 3 years) later
12 Nov 2026Analysed by vulneraibility.com831 days (about 2 years) later

CVSS vector

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

Metric	Value	What it means
Attack vector	NetworkReachable over the internet or any routable network.	Reachable over the internet or any routable network.
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	LowThe attacker needs basic user privileges.	The attacker needs basic user privileges.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2021-31630 being exploited?

Not confirmed. CVE-2021-31630 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 27% probability of exploitation in the next 30 days.

How severe is CVE-2021-31630?

CVE-2021-31630 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2021-31630?

Not known from our data. No patch reference has been recorded for CVE-2021-31630, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.

What does CVE-2021-31630 affect?

CVE-2021-31630 affects openplcproject:openplc_v3_firmware. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

2 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
FIRST EPSS: exploit probability and percentile
PoC-in-GitHub: GitHub repositories that claim a proof of concept

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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