CVE-2026-87853: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-993g-jgf7-rg3x
Share
CVSS 7.5
CWE-187
Published
Advisory Summary

CVE-2026-87853 is a HIGH (CVSS 7.5) security vulnerability vulnerability (CWE-187: Partial String Comparison) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-87853 at a Glance

CVE Identifier CVE-2026-87853
GHSA Identifier GHSA-993g-jgf7-rg3x
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-187: Partial String Comparison
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

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

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

How to Fix CVE-2026-87853

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-2026-87853, 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-187: Partial String Comparison, where the product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses. 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

A flaw was found in SSSD's IdP authentication provider. The eval_access_token_buf() function compares the OIDC subject identifier using strncmp() with the authenticated user's identifier length, performing a prefix comparison instead of an exact match. An attacker whose IdP identifier is a strict prefix of a target user's identifier can authenticate as the target user.

References

NVD — CVE-2026-87853 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-87853
access.redhat.com/errata/rhsa-2026:77... WEB
https://access.redhat.com/errata/RHSA-2026:77534
Software Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-87853
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2530888

Frequently Asked Questions

What is CVE-2026-87853?
CVE-2026-87853 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-187: Partial String Comparison.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-87853?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-87853?
CVE-2026-87853 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-87853?
CVE-2026-87853 is classified under CWE-187: Partial String Comparison (The product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses.).
How can I check Maven dependencies for CVE-2026-87853?
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-993g-jgf7-rg3x",
  "modified" : "2026-10-09T00:31:40Z",
  "published" : "2026-09-09T18:32:05Z",
  "aliases" : [ "CVE-2026-87853" ],
  "details" : "A flaw was found in SSSD's IdP authentication provider. The eval_access_token_buf() function compares the OIDC subject identifier using strncmp() with the authenticated user's identifier length, performing a prefix comparison instead of an exact match. An attacker whose IdP identifier is a strict prefix of a target user's identifier can authenticate as the target user.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-87853"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:77534"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-87853"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2530888"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-187" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-09T17:17:52Z"
  }
}