CVE-2026-2016
Published: 06 February 2026
Summary
CVE-2026-2016 is a medium-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Happyfish100 Libfastcommon. Its CVSS base score is 4.8 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 5.0th 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 are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-2016 is a stack-based buffer overflow vulnerability in the base64_decode function of the src/base64.c file within happyfish100's libfastcommon library, affecting versions up to 1.0.84. The issue was published on 2026-02-06 and is associated with CWEs-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), CWE-121 (Stack-based Buffer Overflow), and CWE-787 (Out-of-bounds Write).
Exploitation requires local access (AV:L), low privileges (PR:L), and low attack complexity (AC:L), with no user interaction needed (UI:N) and no impact on scope (S:U). A successful attack can achieve low impacts on confidentiality, integrity, and availability (C:L/I:L/A:L), resulting in a CVSS 3.1 base score of 5.3 (Medium severity). The exploit has been publicly disclosed and may be used by local attackers.
The recommended mitigation is to apply the patch identified by commit 82f66af3e252e3e137dba0c3891570f085e79adf, available in the libfastcommon GitHub repository. Additional details are documented in GitHub issues #55 and related comments.
Notable context includes the public disclosure of the exploit, with discussions in the libfastcommon GitHub repository and issues.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5685
Vulnerability details
A security vulnerability has been detected in happyfish100 libfastcommon up to 1.0.84. Affected by this vulnerability is the function base64_decode of the file src/base64.c. The manipulation leads to stack-based buffer overflow. Local access is required to approach this attack. The…
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exploit has been disclosed publicly and may be used. The identifier of the patch is 82f66af3e252e3e137dba0c3891570f085e79adf. Applying a patch is the recommended action to fix this issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local stack-based buffer overflow enables code execution for privilege escalation on the host.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely installation of the vendor patch (commit 82f66af3) that eliminates the stack-based buffer overflow in base64_decode.
Enforces memory-protection mechanisms that block out-of-bounds writes on the stack, directly mitigating CWE-121/CWE-787 exploitation.
Restricts the low-privilege local accounts needed to reach and trigger the vulnerable function, reducing the attack surface.