CVE-2026-105959

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The GLZ encoder dictionary restore path truncates a size_t allocation size to int when calling the malloc callback, allowing a malicious authenticated SPICE client during VM live migration to trigger a massive heap buffer overflow by sending a crafted max_encoders value in migration data."}], "affected": [{"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 6", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "spice-server", "defaultStatus": "affected", "cpes": ["cpe:/o:redhat:rhel_els:6"]}, {"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 7", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "spice", "defaultStatus": "affected", "cpes": ["cpe:/o:redhat:rhel_els:7"]}, {"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 8", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "spice", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:enterprise_linux:8"]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-105959", "tags": ["vdb-entry", "x_refsource_REDHAT"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2554008", "name": "RHBZ#2554008", "tags": ["issue-tracking", "x_refsource_REDHAT"]}, {"url": "https://gitlab.freedesktop.org/spice/spice/-/merge_requests/253"}], "datePublic": "2026-10-08T11:00:52.000Z", "problemTypes": [{"descriptions": [{"cweId": "CWE-190", "description": "Integer Overflow or Wraparound", "lang": "en", "type": "CWE"}]}], "x_redhatCweChain": "CWE-190: Integer Overflow or Wraparound", "workarounds": [{"lang": "en", "value": "This vulnerability is only exploitable during VM live migration by an authenticated SPICE client. If live migration is not required, disabling it eliminates the attack surface. If live migration is needed, restrict SPICE client connections to trusted networks using firewall rules and enforce strong authentication (TLS with mutual certificate validation, or SASL with strong credentials) to limit who can connect as a SPICE client.\n\n--- CME Mitigation Guidance (2026-10-20) ---\nDisclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.\n\nThe highest-value action is to prevent integer truncation of size_t allocation calculations to int when invoking the GlzEncoderUsrContext::malloc callback in the GLZ dictionary restore path: upgrade to the fixed Spice/Spice Server builds, which prevent truncation of size_t allocation sizes to int when invoking the GLZ dictionary malloc callback, closing all 2 injection vectors (crafted SPICE_MSGC_MIGRATE_DATA message, malicious max_encoders field in GlzEncDictRestoreData). Until patched, this is a concern on 64-bit Linux hosts running SPICE server, so Disable VM live migration if not required, restrict SPICE client access to trusted networks using firewall rules, and enforce strong authentication via SASL or TLS with mutual certificate validation. As a compensating measure, Run SELinux in enforcing mode to confine the SPICE server process domain and restrict unauthorized system access if the heap overflow is exploited. 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Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.\n\nThe highest-value action is to prevent integer truncation of size_t allocation calculations to int when invoking the GlzEncoderUsrContext::malloc callback in the GLZ dictionary restore path: upgrade to the fixed Spice/Spice Server builds, which prevent truncation of size_t allocation sizes to int when invoking the GLZ dictionary malloc callback, closing all 2 injection vectors (crafted SPICE_MSGC_MIGRATE_DATA message, malicious max_encoders field in GlzEncDictRestoreData). Until patched, this is a concern on 64-bit Linux hosts running SPICE server, so Disable VM live migration if not required, restrict SPICE client access to trusted networks using firewall rules, and enforce strong authentication via SASL or TLS with mutual certificate validation. 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