CVE-2025-15536VulnerabilityPublished 18 Jan 2026Updated 23 Feb 2026

CVE-2025-15536: BYVoid OpenCC · Heap-based Buffer Overflow

Affects BYVoid OpenCCSource CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 07:57 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 16% 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 18 Jan 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 2026-10-26.

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
BYVoidOpenCC	Affected =1.1.0 =1.1.1 =1.1.2 =1.1.3 =1.1.4 =1.1.5 =1.1.6 =1.1.7 =1.1.8 =1.1.9	Fixed in–
GitHubbyvoid/OpenCC`pkg:github/byvoid/OpenCC`Other threats	Affected =1.1.0 =1.1.1 =1.1.2 =1.1.3 =1.1.4 =1.1.5 =1.1.6 =1.1.7 =1.1.8 =1.1.9	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2025-15536, organizations should immediately apply the official patch identified by commit 345c9a50ab07018f1b4439776bad78a0d40778ec to all affected OpenCC installations. Beyond patching, restrict local access to systems running OpenCC to trusted users only, employing strict access controls and monitoring for unusual local activity. Employ application whitelisting and runtime protections to detect and prevent exploitation attempts. Conduct regular code audits and fuzz testing on text processing components to identify similar vulnerabilities proactively. Where possible, run OpenCC processes with the least privileges necessary to limit the impact of potential exploitation. Additionally, maintain up-to-date backups and incident response plans to recover quickly from any exploitation-induced disruptions. Network segmentation can also help isolate vulnerable systems from critical infrastructure. Finally, educate local users and administrators about the risks of executing untrusted code or scripts that might trigger the vulnerability.

Description

A weakness has been identified in BYVoid OpenCC up to 1.1.9. This vulnerability affects the function opencc::MaxMatchSegmentation of the file src/MaxMatchSegmentation.cpp. This manipulation causes heap-based buffer overflow. The attack is restricted to local execution. The exploit has been made available to the public and could be used for attacks. Patch name: 345c9a50ab07018f1b4439776bad78a0d40778ec. To fix this issue, it is recommended to deploy a patch.

Impact

The primary impact of CVE-2025-15536 is the potential for local attackers to cause heap memory corruption, which can lead to application crashes or potentially arbitrary code execution. For organizations, this could result in denial of service conditions on systems running OpenCC, disrupting services that rely on text conversion or segmentation. In scenarios where attackers can escalate privileges or execute code, this could lead to broader system compromise. Since the vulnerability requires local access with some privileges, the risk is mitigated somewhat by access controls, but insider threats or compromised accounts could exploit it. The public availability of exploit code increases the likelihood of exploitation attempts. Organizations using OpenCC in critical language processing pipelines, especially in sectors like government, finance, or telecommunications in East Asia, could face operational disruptions or data integrity issues if exploited. The vulnerability does not affect remote attackers directly, limiting its impact scope but still posing a significant risk in multi-user or shared environments.

References

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