CVE-2026-49953: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-p3qj-vw7q-v9pc
Share
CVSS 6.5
CWE-804
Published
Advisory Summary

CVE-2026-49953 is a MODERATE (CVSS 6.5) security vulnerability vulnerability (CWE-804: Guessable CAPTCHA) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product uses a captcha challenge, but the challenge can be guessed or automatically recognized by a non-human actor.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-49953 at a Glance

CVE Identifier CVE-2026-49953
GHSA Identifier GHSA-p3qj-vw7q-v9pc
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-804: Guessable CAPTCHA
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.5

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

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

How to Fix CVE-2026-49953

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-2026-49953, 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-804: Guessable CAPTCHA, where the product uses a captcha challenge, but the challenge can be guessed or automatically recognized by a non-human actor. 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

Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical character recognition model against collected CAPTCHA samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.

References

NVD — CVE-2026-49953 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49953
Software Security Information SECURITY
https://karmainsecurity.com/KIS-2026-10
Software Security Information SECURITY
https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce
www.vulncheck.com/advisories/discuz-x... WEB
https://www.vulncheck.com/advisories/discuz-x5-0-captcha-bypass-via-predictable-character-set
seclists.org/fulldisclosure/2026... WEB
http://seclists.org/fulldisclosure/2026/Jun/4

Frequently Asked Questions

What is CVE-2026-49953?
CVE-2026-49953 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-804: Guessable CAPTCHA.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-49953?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-49953?
CVE-2026-49953 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-49953?
CVE-2026-49953 is classified under CWE-804: Guessable CAPTCHA (The product uses a CAPTCHA challenge, but the challenge can be guessed or automatically recognized by a non-human actor.).
How can I check Maven dependencies for CVE-2026-49953?
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-p3qj-vw7q-v9pc",
  "modified" : "2026-06-16T12:32:01Z",
  "published" : "2026-06-15T21:30:40Z",
  "aliases" : [ "CVE-2026-49953" ],
  "details" : "Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical character recognition model against collected CAPTCHA samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-49953"
  }, {
    "type" : "WEB",
    "url" : "https://karmainsecurity.com/KIS-2026-10"
  }, {
    "type" : "WEB",
    "url" : "https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/discuz-x5-0-captcha-bypass-via-predictable-character-set"
  }, {
    "type" : "WEB",
    "url" : "http://seclists.org/fulldisclosure/2026/Jun/4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-804" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-06-15T20:16:29Z"
  }
}