VulnerabilityPublished 9 Mar 2026Updated 10 Mar 2026

CVE-2026-3813: opencc JFlow · Injection

Affects opencc JFlowSource CVE Database V5

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Public exploit available · CVSS 5.3 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/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: Network
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: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
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 9 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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
openccJFlow	Affected =5badc00db382d7cb82dad231e6a866b18e0addfe	Fixed in–

AI-suggested

Organizations using opencc JFlow should immediately audit their deployments to identify affected versions, focusing on those at or before commit 5badc00db382d7cb82dad231e6a866b18e0addfe. Employ network-level protections such as web application firewalls (WAFs) configured to detect and block injection patterns targeting JFlow endpoints. Restrict network access to the affected service to trusted internal networks where possible. Monitor logs and network traffic for unusual activity indicative of injection attempts or exploitation. Engage in proactive code review and consider temporary disabling or isolating vulnerable workflow components until a vendor patch or update is released. Maintain communication with the opencc project for updates and apply patches promptly once available. Additionally, consider deploying runtime application self-protection (RASP) tools to detect and block injection attacks in real time.

Description

CVE-2026-3813 is a medium-severity injection vulnerability in the opencc JFlow product, specifically in the Calculate function within src/main/java/bp/wf/httphandler/WF_CCForm.java. The vulnerability allows remote attackers to perform injection attacks without requiring user interaction or elevated privileges. The product uses a rolling release system, making exact affected versions unclear, but the vulnerability affects versions up to commit 5badc00db382d7cb82dad231e6a866b18e0addfe. Although an exploit is publicly available, no known active exploitation has been reported. The vendor has not yet responded to the issue report. This vulnerability could lead to partial compromise of confidentiality, integrity, and availability of affected systems. Organizations using opencc JFlow should prioritize code review, input validation, and monitoring to mitigate potential exploitation risks.

Impact

The injection vulnerability in opencc JFlow could allow remote attackers to manipulate the application's execution, potentially leading to unauthorized data access, data corruption, or denial of service. Since the affected function is part of a workflow HTTP handler, exploitation could disrupt critical business processes or expose sensitive workflow data. The medium severity rating indicates a moderate impact on confidentiality, integrity, and availability, but the ease of remote exploitation without authentication raises the risk of widespread attacks if the software is widely deployed. Organizations relying on opencc JFlow for workflow automation or data processing may face operational disruptions, data integrity issues, or leakage of sensitive information. The public availability of exploit code increases the likelihood of opportunistic attacks, especially in environments lacking robust input validation or network segmentation. The absence of an official patch or vendor guidance further exacerbates the risk, potentially leading to prolonged exposure and increased attack surface.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Mar 2026, 19:09 UTC

Technical details

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