CVE-2026-5066Public exploitNetwork attack vector

Memory corruption via oversized TLS address copy

Published Jun 4, 2026 · Updated Jun 4, 2026

Out-of-bounds write in Zephyr RTOS 4.3 and earlier allows attackers to corrupt memory via an oversized TLS socket address length. tls_session_store() and tls_session_restore() copy caller-sized address data into a fixed-size net_sockaddr object without validating addrlen. Reachability requires TLS session caching and application control of addrlen; the demonstrated result is a device crash, while code execution is unproven.

CVSS severity6.3
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Zephyr RTOS 4.3 and earlier allows attackers to corrupt memory via an oversized TLS socket address length. tls_session_store() and tls_session_restore() copy caller-sized address data into a fixed-size net_sockaddr object without validating addrlen. Reachability requires TLS session caching and application control of addrlen; the demonstrated result is a device crash, while code execution is unproven.

The record

CVE
CVE-2026-5066
Published
Jun 4, 2026
Updated
Jun 4, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-787
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 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=* <=4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=* <=4.3

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.3Zephyr ProjectCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write

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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