CVE-2026-56016: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-r49c-4q8x-x33v
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CVSS 5.9
CWE-338
Published
Advisory Summary

CVE-2026-56016 is a MODERATE (CVSS 5.9) security vulnerability vulnerability (CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product uses a pseudo-random number generator (prng) in a security context, but the prng's algorithm is not cryptographically strong.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-56016 at a Glance

CVE Identifier CVE-2026-56016
GHSA Identifier GHSA-r49c-4q8x-x33v
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.9

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

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

How to Fix CVE-2026-56016

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-2026-56016, 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-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG), where the product uses a pseudo-random number generator (prng) in a security context, but the prng's algorithm is not cryptographically strong. 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

CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources. The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible. An attacker who predicts a session id can impersonate the corresponding session and bypass authentication.

References

NVD — CVE-2026-56016 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56016
metacpan.org/release/markstos/cg... WEB
https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes
metacpan.org/release/markstos/cg... WEB
https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm
Software Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/07/01/6

Frequently Asked Questions

What is CVE-2026-56016?
CVE-2026-56016 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG).
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-56016?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-56016?
CVE-2026-56016 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-56016?
CVE-2026-56016 is classified under CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) (The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.).
How can I check Maven dependencies for CVE-2026-56016?
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-r49c-4q8x-x33v",
  "modified" : "2026-07-01T18:31:47Z",
  "published" : "2026-07-01T09:30:26Z",
  "aliases" : [ "CVE-2026-56016" ],
  "details" : "CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources.\n\nThe generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible.\n\nAn attacker who predicts a session id can impersonate the corresponding session and bypass authentication.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-56016"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/07/01/6"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-338" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-01T08:16:21Z"
  }
}