Authentication Flaw in SSSD's IdP Provider Affects Red Hat Products
CVE-2026-87853

7.5HIGH

Key Information:

Vendor

Red Hat
Status
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Vendor
CVE Published:
9 September 2026

What is CVE-2026-87853?

A vulnerability exists in the IdP authentication provider of SSSD that enables an attacker to authenticate as another user. The issue arises from the eval_access_token_buf() function, which improperly compares the OIDC subject identifier using strncmp(). This results in a prefix-based comparison instead of requiring an exact match, allowing an attacker with a strict prefix of a target user's identifier to gain unauthorized access. This flaw highlights the importance of secure authentication processes to prevent impersonation and protect user data.

References

https://access.redhat.com/security/cve/CVE-2026-87853
vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2530888
issue-trackingx_refsource_REDHAT

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank Moritz Theile for reporting this issue.
.