CVE-2026-87080: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-m8c4-89qh-3j3f
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CVSS 9.1
CWE-1286
Published
Advisory Summary

CVE-2026-87080 is a CRITICAL (CVSS 9.1) security vulnerability vulnerability (CWE-1286: Improper Validation of Syntactic Correctness of Input) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-87080 at a Glance

CVE Identifier CVE-2026-87080
GHSA Identifier GHSA-m8c4-89qh-3j3f
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-1286: Improper Validation of Syntactic Correctness of Input
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:N/A:H).

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 None (I:N)
Availability High (A:H)

How to Fix CVE-2026-87080

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-2026-87080, 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-1286: Improper Validation of Syntactic Correctness of Input, where the product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax. 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

Net::IDN::Punycode::PP versions before 2.590 for Perl decode a truncated label to a name containing a character it never encoded in decode_punycode. The pure-Perl decoder reads one digit at a time with four-argument substr and tests the result with defined to detect the end of the input. substr on an exhausted string returns the empty string rather than undef, so decoding continues past the end. The empty string converts to a digit value below the range, reducing the accumulator, and the decoder derives one extra code point and its position from it. The result is deterministic. The XS backend rejects the same label. Net::IDN::Punycode uses this backend wherever the XS does not build. The two backends disagree about what such a label means, so a sender can pick a label that one installation resolves to a name and another rejects.

References

NVD — CVE-2026-87080 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-87080
Security Fix Commit FIX COMMIT
https://github.com/robrwo/Net-IDN-Encode/commit/48436c7ad2c4d4c6398110e11133754fc476a783.patch
metacpan.org/release/pjcj/net-id... WEB
https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes
Software Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/09/22/15

Frequently Asked Questions

What is CVE-2026-87080?
CVE-2026-87080 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-1286: Improper Validation of Syntactic Correctness of Input.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-87080?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-87080?
CVE-2026-87080 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:N/A:H.
What CWE is associated with CVE-2026-87080?
CVE-2026-87080 is classified under CWE-1286: Improper Validation of Syntactic Correctness of Input (The product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.).
How can I check Maven dependencies for CVE-2026-87080?
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-m8c4-89qh-3j3f",
  "modified" : "2026-09-22T18:33:28Z",
  "published" : "2026-09-22T09:31:12Z",
  "aliases" : [ "CVE-2026-87080" ],
  "details" : "Net::IDN::Punycode::PP versions before 2.590 for Perl decode a truncated label to a name containing a character it never encoded in decode_punycode.\n\nThe pure-Perl decoder reads one digit at a time with four-argument substr and tests the result with defined to detect the end of the input. substr on an exhausted string returns the empty string rather than undef, so decoding continues past the end. The empty string converts to a digit value below the range, reducing the accumulator, and the decoder derives one extra code point and its position from it. The result is deterministic. The XS backend rejects the same label.\n\nNet::IDN::Punycode uses this backend wherever the XS does not build.\n\nThe two backends disagree about what such a label means, so a sender can pick a label that one installation resolves to a name and another rejects.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-87080"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/robrwo/Net-IDN-Encode/commit/48436c7ad2c4d4c6398110e11133754fc476a783.patch"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/09/22/15"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1286" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-22T08:16:40Z"
  }
}