CVE-2021-34600Public exploit

Unauthorized physical access via predictable NFC keys

Published Jan 20, 2022 · Updated Sep 16, 2024

Weak key generation in TELENOT compasX before 32.0 allows physically proximate attackers to clone NFC tags for unauthorized entry. Two AES-key routines seed Borland rand() with the current Unix time through srand(time()), reducing the effective key space to 32 bits. Exposure requires DESFire EV1 or EV2 tags provisioned with affected keys; a PIN requirement can block tag-only entry, while remote access also requires a six-digit password.

CVSS severity5.5
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Weak key generation in TELENOT compasX before 32.0 allows physically proximate attackers to clone NFC tags for unauthorized entry. Two AES-key routines seed Borland rand() with the current Unix time through srand(time()), reducing the effective key space to 32 bits. Exposure requires DESFire EV1 or EV2 tags provisioned with affected keys; a PIN requirement can block tag-only entry, while remote access also requires a six-digit password.

The record

CVE
CVE-2021-34600
Published
Jan 20, 2022
Updated
Sep 16, 2024
Vendor
TELENOT ELECTRONIC GmbH
Product
compasX
Classifications
CWE-335, T1110
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 20, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <32.0

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

TELENOT ELECTRONIC GmbH · compasXversion=unspecified <32.0

Published CVSS scores

5.5CERT VDECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
4.9NVDAV:L/AC:L/Au:N/C:C/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.

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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

CWE-335Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
T1110Brute Force

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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