CVE-2026-5447

Medium

Published: 09 April 2026

Published

09 April 2026

Modified

13 April 2026

KEV Added

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Patch

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CVSS Score v4 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Score 0.0022 12.8th percentile

Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-5447 is a medium-severity Heap-based Buffer Overflow (CWE-122) vulnerability. Its CVSS base score is 6.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 12.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Deeper analysis

CVE-2026-5447 is a heap buffer overflow vulnerability in the wolfSSL library, specifically within the CertFromX509 function. The issue arises from incorrect size handling of the AuthorityKeyIdentifier extension during internal conversion of X.509 certificates, classified under CWE-122.

An attacker capable of supplying a malicious X.509 certificate to an application using the affected wolfSSL component can trigger the heap buffer overflow during certificate processing.

The wolfSSL project has released a fix for this vulnerability via pull request #10112 on GitHub, which corrects the size handling of the AuthorityKeyIdentifier extension. Security practitioners should apply this patch to mitigate the issue.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-21183

Vulnerability details

Heap buffer overflow in CertFromX509 via AuthorityKeyIdentifier size confusion. A heap buffer overflow occurs when converting an X.509 certificate internally due to incorrect size handling of the AuthorityKeyIdentifier extension.

CWE(s): CWE-122

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

Why these techniques?

Heap buffer overflow in X.509 cert parsing enables remote code execution via malicious certificate supply, directly facilitating exploitation against public-facing apps (T1190), client-side execution (T1203), or privilege escalation (T1068).

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