CVE-2021-39237Public exploit

Data disclosure via physically accessible UART shells

Published Nov 3, 2021 · Updated Aug 4, 2024

Information disclosure in HP LaserJet and PageWide printer firmware allows physically proximate attackers to read stored data via UART. Unlocked UART connectors on the communications board expose the UEFI shell and the scanner module's root Linux shell without access controls. Physical access to the printer permits unrestricted shell access and disclosure of stored documents, credentials, and configuration data.

CVSS severity4.6
Medium
EPSS probability2.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in HP LaserJet and PageWide printer firmware allows physically proximate attackers to read stored data via UART. Unlocked UART connectors on the communications board expose the UEFI shell and the scanner module's root Linux shell without access controls. Physical access to the printer permits unrestricted shell access and disclosure of stored documents, credentials, and configuration data.

The record

CVE
CVE-2021-39237
Published
Nov 3, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1200
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.1HPCVSS:3.0/AV:P/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
4.6NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1200Hardware Additions

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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