CVE-2026-19953: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-wf9v-63v3-ff2x
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CVSS 6.5
CWE-1289
Published
Advisory Summary

CVE-2026-19953 is a MODERATE (CVSS 6.5) security vulnerability vulnerability (CWE-1289: Improper Validation of Unsafe Equivalence in Input) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-19953 at a Glance

CVE Identifier CVE-2026-19953
GHSA Identifier GHSA-wf9v-63v3-ff2x
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-1289: Improper Validation of Unsafe Equivalence in Input
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-2026-19953

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-2026-19953, 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-1289: Improper Validation of Unsafe Equivalence in Input, where the product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value. 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

URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep. nameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label. Any caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.

References

NVD — CVE-2026-19953 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-19953
Software Source Repository REPOSITORY
https://github.com/libwww-perl/URI/pull/191
Security Fix Commit FIX COMMIT
https://github.com/libwww-perl/URI/commit/956619a9e94f86d8d2c529b4e06a3674c54a73e7.patch
metacpan.org/release/oalders/uri... WEB
https://metacpan.org/release/OALDERS/URI-5.36/changes
www.rfc-editor.org/rfc/rfc5891 WEB
https://www.rfc-editor.org/rfc/rfc5891#section-5.2
Software Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/08/31/14

Frequently Asked Questions

What is CVE-2026-19953?
CVE-2026-19953 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-1289: Improper Validation of Unsafe Equivalence in Input.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-19953?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-19953?
CVE-2026-19953 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-2026-19953?
CVE-2026-19953 is classified under CWE-1289: Improper Validation of Unsafe Equivalence in Input (The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.).
How can I check Maven dependencies for CVE-2026-19953?
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-wf9v-63v3-ff2x",
  "modified" : "2026-09-01T18:30:35Z",
  "published" : "2026-08-31T18:31:31Z",
  "aliases" : [ "CVE-2026-19953" ],
  "details" : "URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep.\n\nnameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label.\n\nAny caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-19953"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/libwww-perl/URI/pull/191"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/libwww-perl/URI/commit/956619a9e94f86d8d2c529b4e06a3674c54a73e7.patch"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/OALDERS/URI-5.36/changes"
  }, {
    "type" : "WEB",
    "url" : "https://www.rfc-editor.org/rfc/rfc5891#section-5.2"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/08/31/14"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1289" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-31T18:17:14Z"
  }
}