Bug 2490288 (CVE-2026-12610)

Summary: CVE-2026-12610 sssd: Use-after-free crash in SSSD' 'sssd_pam' process
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in sssd. When authenticating with a YubiKey, the SSSD PAM responder can crash due to a use-after-free vulnerability, where a memory pointer is incorrectly handled. A local attacker could exploit this flaw by manipulating smartcard or YubiKey contents, leading to a denial of service that disrupts authentication. This vulnerability also presents a potential for privilege escalation, although it is difficult to exploit.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2494777, 2494800    
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Description OSIDB Bzimport 2026-06-18 11:36:18 UTC 
When authenticating with a YubiKey, the SSSD PAM responder crashes inside sss_certmap_match_cert because the sss_certmap_ctx pointer passed to it has already been freed and reused for string data from the p11_child response.
The pointer value 0x6e65687475412056 decodes to ASCII "V Auth en" which is part from the certificate label "X.509 Certificate for PIV Authentication" returned by p11_child. This confirms that the freed sss_certmap_ctx memory was reused during response parsing.

Root cause:
sss_certmap_ctx is owned by the PAM request state. If the request is cancelled or completes while the asynchronous p11_child process is still running, the request state (and the context) is freed. When the child eventually returns and p11_child_done / parse_p11_child_response run, they call sss_certmap_match_cert with a dangling pointer. The certificate data (token name, label, or certificate contents) then occupies the freed memory.

Impact:
Denial of service: The PAM responder crashes, breaking authentication in some cases.
Potential privilege escalation: Because an attacker controls the smartcard/YubiKey contents, they can influence the data that replaces the freed sss_certmap_ctx structure, turning this into a controlled use-after-free in a privileged, long-running process (although this looks hard to exploit).