JFlow: Improper Neutralization of Special Elements used in a Command
CVE-2026-3813 is a critical-severity improper neutralization of special elements used in a command vulnerability in JFlow from Opencc, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected JFlow versions: 5badc00db382d7cb82dad231e6a866b18e0addfe. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of JFlow you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on gitee.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 2.1 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 6.3 | Medium | CNA (vuldb.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 2.0 | 6.5 | Medium | CNA (vuldb.com) |
Official description
A vulnerability was identified in opencc JFlow up to 5badc00db382d7cb82dad231e6a866b18e0addfe. Affected by this vulnerability is the function Calculate of the file src/main/java/bp/wf/httphandler/WF_CCForm.java. Such manipulation leads to injection. The attack may be performed from remote. The exploit is publicly available and might be used. This product utilizes a rolling release system for continuous delivery, and as such, version information for affected or updated releases is not disclosed. The project was informed of the problem early through an issue report but has not responded yet.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in a Command
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- If possible, ensure that all external commands called from the program are statically created.
- Run time: Run time policy enforcement may be used in an allowlist fashion to prevent use of any non-sanctioned commands.
More Improper Neutralization of Special Elements used in a Command vulnerabilities (CWE-77)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- gitee.com/opencc/JFlow/issues/IE8R2FExploit, Issue Tracking
Third-party and government advisories
- vuldb.com/?id.349779Third Party Advisory, VDB Entry
- vuldb.com/?submit.769112Third Party Advisory, VDB Entry
Other references
- gitee.com/opencc/JFlow/Product
- vuldb.com/?ctiid.349779Permissions Required, VDB Entry
Recent Improper Neutralization of Special Elements used in a Command vulnerabilities
- 7.2 High severity
- 7.2 High severity
- 8.8 High severity
- 8.1 High severity
- 8.8 High severity
- 8.8 High severity
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