--- cve: "CVE-2026-64034" severity: "CRITICAL" cvss: 9.3 epss: "15%" vendor: "Linux" kev: false exploited: false published: "2026-07-19 16:17:43" tags: [cve, security, critical] source: tsecurity.de CVE-Dossier exported: "2026-09-15T01:19:38+02:00" --- # CVE-2026-64034 > 9.3 CRITICAL ## Beschreibung In the Linux kernel, the following vulnerability has been resolved: net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp() re-reads the same field from the same DMA buffer for test_bit() and pointer arithmetic. DMA-coherent memory is mapped uncacheable on x86 and is shared, unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes directly to host-visible memory. A H/W can modify the value between the check and the use, bypassing the bounds validation. Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a stack-local variable in mana_hwc_rx_event_handler(), and passing the validated value as a parameter to mana_hwc_handle_resp(). ## CVSS-Vektor ``` CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H ``` | Metrik | Wert | Bewertung | |---|---|---| | AV Angriffsvektor | Lokal | good | | AC Komplexität | Gering | bad | | PR Privilegien | Keine | bad | | UI Interaktion | Keine | bad | | S Scope | Verändert | bad | | C Vertraulichkeit | Hoch | bad | | I Integrität | Hoch | bad | | A Verfügbarkeit | Hoch | bad | ## Patch verfügbar (OSV) - Kernel ≥ 5.15.209 - Kernel ≥ 6.1.175 - Kernel ≥ 6.6.142 - Kernel ≥ 6.12.92 - Kernel ≥ 6.18.34 - Kernel ≥ 7.0.11 ## Referenzen - - - - - - - --- _Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-64034) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_