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Sssd: sssd: idp authentication prefix comparison allows cross-user impersonation

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-87853

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-87853

Red Hat Enterprise Linux 10

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat Enterprise Linux 6

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat Enterprise Linux 7

Source reference: /containers/cna/affected/2/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat Enterprise Linux 8

Source reference: /containers/cna/affected/3/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat Enterprise Linux 9

Source reference: /containers/cna/affected/4/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat OpenShift Container Platform 4

Source reference: /containers/cna/affected/5/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Red Hat OpenShift Container Platform 4

Source reference: /containers/cna/affected/6/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:10.2"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 10",
    "versions": [
      {
        "status": "unaffected",
        "version": "0:2.12.0-3.el10_2.2",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "sssd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:6"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 6",
    "packageName": "sssd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unknown"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:7"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 7",
    "packageName": "sssd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unaffected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:8"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 8",
    "packageName": "sssd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unaffected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:9"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 9",
    "packageName": "sssd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4",
    "packageName": "openshift/ose-rhel-coreos-8",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unaffected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4",
    "packageName": "openshift/ose-rhel-coreos-9",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unaffected"
  }
]
Related CVEs
CVE-2026-87853

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#49404 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement