CVE-2021-22811
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability exists that could cause script execution when the request of a privileged account accessing the vulnerable web page is intercepted. Affected Products: 1-Phase Uninterruptible Power Supply (UPS) using NMC2 including Smart-UPS, Symmetra, and Galaxy 3500 with Network Management Card 2 (NMC2): AP9630/AP9630CH/AP9630J, AP9631/AP9631CH/AP9631J, AP9635/AP9635J (NMC2 AOS V6.9.8 and earlier), 3-Phase Uninterruptible Power Supply (UPS) using NMC2 including Symmetra PX 250/500 (SYPX) Network Management Card 2 (NMC2): AP9630/AP9630CH/AP9630J, AP9631/AP9631CH/AP9631J, AP9635/AP9635J (NMC2 AOS V6.9.6 and earlier), 3-Phase Uninterruptible Power Supply (UPS) using NMC2 including Symmetra PX 48/96/100/160 kW UPS (PX2), Symmetra PX 20/40 kW UPS (SY3P), Gutor (SXW, GVX), and Galaxy (GVMTS, GVMSA, GVXTS, GVXSA, G7K, GFC, G9KCHU): AP9630/AP9630CH/AP9630J, AP9631/AP9631CH/AP9631J, AP9635/AP9635CH (NMC2 AOS V6.9.6 and earlier), 1-Phase Uninterruptible Power Supply (UPS) using NMC3 including Smart-UPS, Symmetra, and Galaxy 3500 with Network Management Card 3 (NMC3): AP9640/AP9640J, AP9641/AP9641J, AP9643/AP9643J (NMC3 AOS V1.4.2.1 and earlier), APC Rack Power Distribution Units (PDU) using NMC2 2G Metered/Switched Rack PDUs with embedded NMC2: AP84XX, AP86XX, AP88XX, AP89XX (NMC2 AOS V6.9.6 and earlier), APC Rack Power Distribution Units (PDU) using NMC3 2G Metered/Switched Rack PDUs with embedded NMC3: APDU99xx (NMC3 AOS V1.4.0 and earlier), APC 3-Phase Power Distribution Products using NMC2 Galaxy RPP: GRPPIP2X84 (NMC2 AOS V6.9.6 and earlier), Network Management Card 2 (NMC2) for InfraStruxure 150 kVA PDU with 84 Poles (X84P): PDPB150G6F (NMC2 AOS V6.9.6 and earlier), Network Management Card 2 for InfraStruxure 40/60kVA PDU (XPDU) PD40G6FK1-M, PD40F6FK1-M, PD40L6FK1-M, PDRPPNX10 M,PD60G6FK1, PD60F6FK1, PD60L6FK1, PDRPPNX10, PD40E5EK20-M, PD40H5EK20-M (NMC2 AOS V6.9.6 and earlier), Network Management Card 2 for Modular 150/175kVA PDU (XRDP): PDPM150G6F, PDPM150L6F, PDPM175G6H (NMC2 AOS V6.9.6 and earlier), Network Management Card 2 for 400 and 500 kVA (PMM): PMM400-ALA, PMM400-ALAX, PMM400-CUB, PMM500-ALA, PMM500-ALAX, PMM500-CUB (NMC2 AOS V6.9.6 and earlier), Network Management Card 2 for Modular PDU (XRDP2G): PDPM72F-5U, PDPM138H-5U, PDPM144F, PDPM138H-R, PDPM277H, PDPM288G6H (NMC2 AOS V6.9.6 and earlier), Rack Automatic Transfer Switches (ATS) Embedded NMC2: Rack Automatic Transfer Switches - AP44XX (ATS4G) (NMC2 AOS V6.9.6 and earlier), Network Management Card 2 (NMC2) Cooling Products: InRow Cooling for series ACRP5xx, ACRP1xx, ACRD5xx, and ACRC5xx SKUs (ACRP2G), InRow Cooling for series ACRC10x SKUs (RC10X2G), InRow Cooling for series ACRD6xx and ACRC6xx SKUs (ACRD2G), InRow Cooling Display for series ACRD3xx (ACRC2G), InRow Cooling for series ACSC1xx SKUs (SC2G), InRow Cooling for series ACRD1xx and ACRD2xx (ACRPTK2G), Ecoflair IAEC25/50 Air Economizer Display (EB2G), Uniflair SP UCF0481I, UCF0341I (UNFLRSP), Uniflair LE DX Perimeter Cooling Display for SKUs: IDAV, IDEV, IDWV, IUAV, IUEV, IUWV, IXAV, IXEV, IXWV, LDAV, LDEV, and LDWV (LEDX2G), Refrigerant Distribution Unit: ACDA9xx (RDU) (NMC2 AOS V6.9.6 and earlier), Environmental Monitoring Unit with embedded NMC2 (NB250): NetBotz NBRK0250 (NMC2 AOS V6.9.6 and earlier), and Network Management Card 2 (NMC2): AP9922 Battery Management System (BM4) (NMC2 AOS V6.9.6 and earlier)
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCWE-79 Cross-site Scripting (XSS) vulnerability in APC Network Management Card 2 (NMC2) and NMC3 web interfaces. The vulnerability allows script execution when requests from privileged accounts accessing vulnerable web pages are intercepted, indicating a stored or reflected XSS in the management interface used across UPS systems, PDUs, and cooling equipment.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 6.9.8<= 6.9.6<= 1.4.2.1<= 1.4.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the Network Management Card firmware versionAccess the APC web interface and navigate to the About or System Information page to view the NMC firmware version, or use SNMP/CLI to query the firmware version (e.g., snmpget for sysDescr or use apcphd command)Affected if The displayed firmware version is NMC2 <= 6.9.8 or <= 6.9.6, or NMC3 <= 1.4.2.1 or <= 1.4.0
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Confirm the NMC generation (NMC2 or NMC3)Check the product name or model in the web interface About page, or examine the firmware file name/version string - NMC2 typically shows versions like 6.x.x while NMC3 shows 1.x.xAffected if The device uses NMC2 or NMC3 firmware versioning
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Verify the web interface is enabledCheck the Network Configuration settings in the NMC web interface under Network > HTTP(WEB) or verify port 80/443 is accessible on the deviceAffected if HTTP or HTTPS web access is enabled on the management card
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Check for privileged account usageReview user accounts configured on the NMC - the vulnerability affects requests from privileged (administrator/operator) accounts accessing vulnerable pagesAffected if Privileged user accounts exist and have access to the web interface
You are affected if your APC Network Management Card runs NMC2 firmware version 6.9.8 or earlier (6.9.6 or earlier) or NMC3 firmware version 1.4.2.1 or earlier (1.4.0 or earlier) and the web interface is accessible to privileged accounts.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate NMC2 AOS to versions newer than V6.9.8 (NMC2) or NMC3 AOS to versions newer than V1.4.2.1/V1.4.0 depending on product model. Apply Schneider Electric security patches and verify firmware integrity.
- Consultation8.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-22811 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-22811 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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