CVE-2026-32953

Key reuse via overwritten USS-enabled flag

Published Mar 20, 2026 · Updated Mar 20, 2026

Protocol implementation error in Tillitis tkeyclient before 1.3.0 allows physically proximate attackers to derive keys without the supplied USS. In loadApp, copy writes the 32-byte BLAKE2s digest at tx[6], overwriting the use-USS flag at the same index with the digest's first byte. A digest beginning with 0x00 disables USS use, so the resulting CDI and keys match operation without a USS; reaching the flaw requires a connected TKey and a supplied secret.

CVSS severity4.7
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protocol implementation error in Tillitis tkeyclient before 1.3.0 allows physically proximate attackers to derive keys without the supplied USS. In loadApp, copy writes the 32-byte BLAKE2s digest at tx[6], overwriting the use-USS flag at the same index with the digest's first byte. A digest beginning with 0x00 disables USS use, so the resulting CDI and keys match operation without a USS; reaching the flaw requires a connected TKey and a supplied secret.

The record

CVE
CVE-2026-32953
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
Tillitis
Product
tkeyclient
Classifications
CWE-303
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record 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=< 1.3.0

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Tillitis · tkeyclientversion=< 1.3.0

Published CVSS scores

4.6NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
4.7GitHubCVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:H

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-303Incorrect Implementation of Authentication Algorithm

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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