Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | sssd | No fix yet | — |
| Debian 13 | sssd | No fix yet | — |
| Debian 12 | sssd | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | sssd | No fix yet | — |
| Ubuntu 26.04 LTS | sssd | No fix yet | — |
| Ubuntu 24.04 LTS | sssd | No fix yet | — |
| Ubuntu 22.04 LTS | sssd | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | sssd | No fix yet | — |
| Ubuntu Pro 18.04 LTS | sssd | No fix yet | — |
| Ubuntu Pro 16.04 LTS | sssd | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | sssd +28 | 2.12.0-3.el10_2.2 | RHSA-2026:98559, RHSA-2026:77534 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | sssd +28 | 2.12.0-3.el10_2.2 | ALSA-2026:77534 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | sssd | 2.12.0-3.el10_2.2 | RLSA-2026:98559, RLSA-2026:77534 |
| Rocky Linux 10 | sssd-ad +27 | 2.13.1-3.el10_3 | RLSA-2026:98559 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | sssd | 2.13.1-3.1 | openSUSE-SU-2026:11825-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | sssd +28 | 2.12.0-3.0.1.el10_2.2 | ELSA-2026-77534 |
Advisories 8
- RHSA-2026:98559 Red Hat Security Advisory: sssd security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RLSA-2026:98559 Moderate: sssd security, bug fix, and enhancement update Rocky Linux Security Advisories · Nov 13, 2026
- WID-SEC-2026-3848 Red Hat Enterprise Linux (sssd, tftp, ansible-collection-ansible-posix): Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- ALSA-2026:77534 Moderate: sssd security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:77534 Red Hat Security Advisory: sssd security update Red Hat Security Advisories (RHSA) · Oct 10, 2026
- RLSA-2026:77534 Moderate: sssd security update Rocky Linux Security Advisories · Oct 9, 2026
- ELSA-2026-77534 Moderate: sssd security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 8, 2026
- openSUSE-SU-2026:11825-1 libipa_hbac-devel-2.13.1-3.1 on GA media SUSE / openSUSE Security Updates · Sep 20, 2026
References
- RHSA-2026:77534 vendor-advisory
- RHSA-2026:98559 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-87853 vdb-entry
- RHBZ#2530888 issue-tracking