VulnerabilityPublished 6 Feb 2026Updated 23 Feb 2026

CVE-2026-2016: happyfish100 libfastcommon · Stack-based Buffer Overflow

Affects happyfish100 libfastcommonSource CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 09:16 UTC

CVSS 4.0 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Local
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
happyfish100libfastcommon	Affected =1.0.0 =1.0.1 =1.0.2 =1.0.3 =1.0.4 =1.0.5 =1.0.6 =1.0.7 =1.0.8 =1.0.9 =1.0.10 =1.0.11 =1.0.12 =1.0.13 =1.0.14 =1.0.15 =1.0.16 =1.0.17 =1.0.18 =1.0.19 =1.0.20 =1.0.21 =1.0.22 =1.0.23 =1.0.24 =1.0.25 =1.0.26 =1.0.27 =1.0.28 =1.0.29 =1.0.30 =1.0.31 =1.0.32 =1.0.33 =1.0.34 =1.0.35 =1.0.36 =1.0.37 =1.0.38 =1.0.39 =1.0.40 =1.0.41 =1.0.42 =1.0.43 =1.0.44 =1.0.45 =1.0.46 =1.0.47 =1.0.48 =1.0.49 =1.0.50 =1.0.51 =1.0.52 =1.0.53 =1.0.54 =1.0.55 =1.0.56 =1.0.57 =1.0.58 =1.0.59 =1.0.60 =1.0.61 =1.0.62 =1.0.63 =1.0.64 =1.0.65 =1.0.66 =1.0.67 =1.0.68 =1.0.69 =1.0.70 =1.0.71 =1.0.72 =1.0.73 =1.0.74 =1.0.75 =1.0.76 =1.0.77 =1.0.78 =1.0.79 =1.0.80 =1.0.81 =1.0.82 =1.0.83 =1.0.84	Fixed in–
GitHubhappyfish100/libfastcommon`pkg:github/happyfish100/libfastcommon`Other threats	Affected <=1.0.84	Fixed in–

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AI-suggested

To mitigate CVE-2026-2016, organizations should promptly apply the official patch identified by commit 82f66af3e252e3e137dba0c3891570f085e79adf to all affected versions of libfastcommon up to 1.0.84. Additionally, organizations should audit their software dependencies to identify any applications or services that incorporate libfastcommon and ensure they are updated accordingly. Implementing strict access controls to limit local user privileges can reduce the risk of exploitation. Employing runtime protections such as stack canaries, address space layout randomization (ASLR), and control flow integrity (CFI) can help mitigate the impact of buffer overflow vulnerabilities. Regularly monitoring system logs for unusual activity related to base64 decoding functions may provide early detection of exploitation attempts. Finally, maintaining an up-to-date inventory of software components and applying security patches in a timely manner are essential best practices.

Description

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 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.

Impact

The primary impact of this vulnerability is the potential for local attackers to execute arbitrary code or cause application crashes through a stack-based buffer overflow. This can lead to denial of service or privilege escalation if the vulnerable application runs with elevated privileges. However, the requirement for local access and low privileges limits the scope of exploitation, reducing the risk of widespread remote attacks. Organizations using libfastcommon in critical systems or embedded devices may face operational disruptions or security breaches if the vulnerability is exploited. The medium severity rating reflects the moderate risk posed by this vulnerability, emphasizing the importance of patching to maintain system integrity and availability. Since no known exploits are currently in the wild, the window for proactive mitigation is still open, but the public disclosure increases the likelihood of future exploitation attempts.

References

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