CVE-2021-3435

Memory disclosure via incomplete L2CAP response initialization

Published Jun 28, 2022 · Updated Sep 16, 2024

Use of uninitialized data in Zephyr RTOS 2.4.0 through 2.5.x allows local users to read residual memory through an L2CAP response. In le_ecred_conn_req(), partial connection failures omit destination channel identifiers while response storage remains incompletely initialized. The Bluetooth host must process an Enhanced Credit Based Connection request; the reported consequence is confidentiality loss only.

CVSS severity4.0
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of uninitialized data in Zephyr RTOS 2.4.0 through 2.5.x allows local users to read residual memory through an L2CAP response. In le_ecred_conn_req(), partial connection failures omit destination channel identifiers while response storage remains incompletely initialized. The Bluetooth host must process an Enhanced Credit Based Connection request; the reported consequence is confidentiality loss only.

The record

CVE
CVE-2021-3435
Published
Jun 28, 2022
Updated
Sep 16, 2024
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-908, T1005
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 28, 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=v2.4.0 <unspecified
  2. Affected versionversion=v2.5.0 <unspecified

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=v2.4.0 <unspecified; version=v2.5.0 <unspecified

Published CVSS scores

3.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.0Zephyr ProjectCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
2.1NIST NVDAV:L/AC:L/Au:N/C:P/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
T1005Data from Local System

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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