Crash via unsynchronized TLS session cache access
Published Sep 14, 2026 · Updated Sep 14, 2026
Use-after-free in Zephyr RTOS 3.1.0 through 4.4.1 allows remote attackers to crash TLS clients through concurrent session-cache access. The process-global client_cache uses per-socket locks, allowing one socket to free an entry->session buffer while another socket loads or evicts that entry. The race requires the off-by-default TLS_SESSION_CACHE option and concurrent client sockets; a malicious server can increase ticket timing pressure, and exploitation corrupts the mbedTLS heap or crashes the device.
Summary
What happened
Use-after-free in Zephyr RTOS 3.1.0 through 4.4.1 allows remote attackers to crash TLS clients through concurrent session-cache access. The process-global client_cache uses per-socket locks, allowing one socket to free an entry->session buffer while another socket loads or evicts that entry. The race requires the off-by-default TLS_SESSION_CACHE option and concurrent client sockets; a malicious server can increase ticket timing pressure, and exploitation corrupts the mbedTLS heap or crashes the device.
The record
- CVE
- CVE-2026-15924
- Published
- Sep 14, 2026
- Updated
- Sep 14, 2026
- Vendor
- Zephyr Project
- Product
- Zephyr RTOS
- Classifications
- T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 14, 2026CVE publishedPublication date reported by the CVE source.
- Sep 14, 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?
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- Affected versionversion=3.1.0 <4.4.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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