CVE-2026-75870: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-3679-xr9w-9625
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CVSS 9.1
CWE-1394
Published
Advisory Summary

CVE-2026-75870 is a CRITICAL (CVSS 9.1) security vulnerability vulnerability (CWE-1394: Use of Default Cryptographic Key) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product uses a default cryptographic key for potentially critical functionality.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-75870 at a Glance

CVE Identifier CVE-2026-75870
GHSA Identifier GHSA-3679-xr9w-9625
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-1394: Use of Default Cryptographic Key
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.1

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:H/I:H/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 High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-75870

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-2026-75870, 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-1394: Use of Default Cryptographic Key, where the product uses a default cryptographic key for potentially critical functionality. 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

Punk versions before 0.18 for Perl allow session cookie forgery via an empty default HMAC key when a session is declared without a secret. The session keyword freezes its options onto the application as given: it does not require a secret, warn, or refuse to start when one is absent. The cookie read and the write-back both default that key to the empty string, so a declaration with no secret option, or with an undefined or empty one, signs and verifies with a zero-length HMAC-SHA256 key. An attacker who knows the cookie format can then mint one offline carrying any contents the session holds, such as a user identifier or a role. Nothing marks the misconfiguration at runtime: cookies are well formed and sessions round-trip as expected.

References

NVD — CVE-2026-75870 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-75870
metacpan.org/release/lnation/pun... WEB
https://metacpan.org/release/LNATION/Punk-0.17/source/include/punk/punk_session.h
metacpan.org/release/lnation/pun... WEB
https://metacpan.org/release/LNATION/Punk-0.17/view/lib/Punk.pm
metacpan.org/release/lnation/pun... WEB
https://metacpan.org/release/LNATION/Punk-0.18/source/Changes
Software Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/08/22/5

Frequently Asked Questions

What is CVE-2026-75870?
CVE-2026-75870 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-1394: Use of Default Cryptographic Key.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-75870?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-75870?
CVE-2026-75870 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-75870?
CVE-2026-75870 is classified under CWE-1394: Use of Default Cryptographic Key (The product uses a default cryptographic key for potentially critical functionality.).
How can I check Maven dependencies for CVE-2026-75870?
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-3679-xr9w-9625",
  "modified" : "2026-08-25T21:31:21Z",
  "published" : "2026-08-22T15:31:03Z",
  "aliases" : [ "CVE-2026-75870" ],
  "details" : "Punk versions before 0.18 for Perl allow session cookie forgery via an empty default HMAC key when a session is declared without a secret.\n\nThe session keyword freezes its options onto the application as given: it does not require a secret, warn, or refuse to start when one is absent. The cookie read and the write-back both default that key to the empty string, so a declaration with no secret option, or with an undefined or empty one, signs and verifies with a zero-length HMAC-SHA256 key.\n\nAn attacker who knows the cookie format can then mint one offline carrying any contents the session holds, such as a user identifier or a role. Nothing marks the misconfiguration at runtime: cookies are well formed and sessions round-trip as expected.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-75870"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/LNATION/Punk-0.17/source/include/punk/punk_session.h"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/LNATION/Punk-0.17/view/lib/Punk.pm"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/LNATION/Punk-0.18/source/Changes"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/08/22/5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1394" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-22T14:16:33Z"
  }
}