CVE-2026-33263: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-9rqj-cvwq-v6qh
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CVSS 4.3
CWE-403
Published
Advisory Summary

CVE-2026-33263 is a MODERATE (CVSS 4.3) security vulnerability vulnerability (CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')) affecting Software libraries in the Maven ecosystem. The weakness occurs when a process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized i/o operations using those descriptors.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-33263 at a Glance

CVE Identifier CVE-2026-33263
GHSA Identifier GHSA-9rqj-cvwq-v6qh
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 4.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2026-33263

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-33263, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak'), where a process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized i/o operations using those descriptors. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

References

NVD — CVE-2026-33263 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33263
Software Security Information SECURITY
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json

Frequently Asked Questions

What is CVE-2026-33263?
CVE-2026-33263 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-33263?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-33263?
CVE-2026-33263 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2026-33263?
CVE-2026-33263 is classified under CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak') (A process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized I/O operations using those descriptors.).
How can I check Maven dependencies for CVE-2026-33263?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9rqj-cvwq-v6qh",
  "modified" : "2026-08-28T12:30:25Z",
  "published" : "2026-08-28T12:30:25Z",
  "aliases" : [ "CVE-2026-33263" ],
  "details" : "When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33263"
  }, {
    "type" : "WEB",
    "url" : "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-403" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-28T12:16:27Z"
  }
}