CVE-2026-10655Network attack vector

Networking crash via unsynchronized SNTP socket close

Published Jun 30, 2026 · Updated Jun 30, 2026

Use-after-free in Zephyr RTOS 4.2.0 through 4.4.0 allows remote attackers to crash the networking thread via delayed SNTP replies. The sntp_close_async function closes a UDP socket from the calling thread while the socket-service poll thread retains a k_poll_event pointer into the freed, reusable net_context. A network peer or off-path attacker needs only to drop or delay an SNTP response to exercise the normal timeout path; repeated races interrupt networking and can corrupt reused context memory.

CVSS severity6.5
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Zephyr RTOS 4.2.0 through 4.4.0 allows remote attackers to crash the networking thread via delayed SNTP replies. The sntp_close_async function closes a UDP socket from the calling thread while the socket-service poll thread retains a k_poll_event pointer into the freed, reusable net_context. A network peer or off-path attacker needs only to drop or delay an SNTP response to exercise the normal timeout path; repeated races interrupt networking and can corrupt reused context memory.

The record

CVE
CVE-2026-10655
Published
Jun 30, 2026
Updated
Jun 30, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-416, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 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=4.2.0 <4.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=4.2.0 <4.5.0

Published CVSS scores

6.5Zephyr ProjectCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A: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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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