Cyber Resilience

CVE-2026-5590

Memory Safety in Zephyrproject Zephyr ≤ 4.3.0

Public PoCMemory Safety
Published
05 April 2026
Modified
24 July 2026
Patch / advisory
CVSS Score v3.1 6.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
EPSS Score 0.0020 10th percentile
Risk Priority 38 floored blend · peak EPSS

Summary

CVE-2026-5590 is a medium-severity NULL Pointer Dereference (CWE-476) vulnerability in Zephyrproject Zephyr. Its CVSS base score is 6.4 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 10th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-16 (Memory Protection) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

A race condition during TCP connection teardown can cause tcp_recv() to operate on a connection that has already been released. If tcp_conn_search() returns NULL while processing a SYN packet, a NULL pointer derived from stale context data is passed to…

more

tcp_backlog_is_full() and dereferenced without validation, leading to a crash.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
Why these techniques?

NULL pointer dereference in TCP stack processing (SYN packet) directly enables remote exploitation to crash the endpoint.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-10593Same product: Zephyrproject Zephyr
CVE-2026-10648Same product: Zephyrproject Zephyr
CVE-2026-10656Same product: Zephyrproject Zephyr
CVE-2026-13351Same product: Zephyrproject Zephyr
CVE-2026-10637Same product: Zephyrproject Zephyr
CVE-2026-10640Same product: Zephyrproject Zephyr
CVE-2026-10651Same product: Zephyrproject Zephyr
CVE-2026-10668Same product: Zephyrproject Zephyr
CVE-2026-10655Same product: Zephyrproject Zephyr
CVE-2026-10657Same product: Zephyrproject Zephyr

Affected Assets

zephyrproject
zephyr
≤ 4.3.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SI-16 Memory Protection
  • SI-11 Error Handling
Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly requires validation of inputs/return values (e.g., tcp_conn_search result) before any dereference, blocking the NULL pointer path that triggers the crash.

prevent

Enforces memory protection mechanisms that can intercept or contain invalid pointer dereferences arising from the race condition on released TCP state.

prevent

Requires robust error handling for unexpected NULL or invalid states during TCP processing, preventing the unvalidated call to tcp_backlog_is_full.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (static analysis, code review, safe coding standards) directly prevent NULL dereference bugs during development.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

detects

Security testing can detect NULL dereference defects before release.

prevents

Secure SDLC mandates defensive coding practices that can prevent NULL dereferences.

prevents

Application security requirements can specify input validation and pointer-safety rules.

prevents

Secure architecture principles encourage defensive design that avoids unsafe pointer use.

prevents

Secure coding standards directly require NULL-pointer checks and safe dereference patterns.

References