--- cve: "CVE-2026-90413" severity: "CRITICAL" cvss: 9.1 epss: "0.8%" vendor: "Linux" kev: false exploited: false published: "2026-09-17 17:17:43" tags: [cve, security, critical] source: tsecurity.de CVE-Dossier exported: "2026-09-20T23:27:37+02:00" --- # CVE-2026-90413 > 9.1 CRITICAL ## Beschreibung In the Linux kernel, the following vulnerability has been resolved: IB/isert: reject login PDUs declaring more data than was received isert_login_recv_done() records how many bytes the HCA actually placed in the login buffer, but nothing compares that against the length the login PDU's BHS declares. isert_rx_login_req() copies min(login_req_len, MAX_KEY_VALUE_PAIRS) bytes into login->req_buf, and the login code then reads the declared length back out of that buffer - for the first PDU in iscsi_target_locate_portal(), payload_length = ntoh24(login_req->dlength); tmpbuf = kmemdup_nul(login->req_buf, payload_length, GFP_KERNEL); and for the ones after it in iscsi_decode_text_input(), reached from iscsi_target_do_login(). login->req_buf is a fixed MAX_KEY_VALUE_PAIRS (8192) byte allocation, so an initiator that declares more than it sends reads off the end of it, before authentication and with the length under its control: BUG: KASAN: slab-out-of-bounds in kmemdup_nul+0x43/0x80 Read of size 8193 at addr ffff8881056a8000 by task iscsi_np/167 __asan_memcpy+0x23/0x60 kmemdup_nul+0x43/0x80 iscsi_target_locate_portal+0x48d/0x1180 iscsi_target_login_thread+0x19a9/0x3350 Allocated by task 167: __kmalloc_cache_noprof+0x158/0x370 iscsi_target_login_thread+0x971/0x3350 which belongs to the cache kmalloc-8k of size 8192 allocated 8192-byte region Falsifying the second login PDU instead reaches the other reader, on the same buffer: BUG: KASAN: slab-out-of-bounds in kmemdup_nul+0x43/0x80 Read of size 8193 at addr ffff888104d10000 by task kworker/1:1/50 Workqueue: isert_login_wq iscsi_target_do_login_rx __asan_memcpy+0x23/0x60 kmemdup_nul+0x43/0x80 iscsi_decode_text_input+0xc6/0x11c0 iscsi_target_do_login+0x261/0x1470 iscsi_target_do_login_rx+0x51d/0x7d0 iscsit over TCP is not exposed: iscsit_get_login_rx() validates the declared length with iscsi_target_check_login_request() and then reads exactly that many bytes off the socket, so the declared length governs how much arrives rather than how much is copied out of an already-filled buffer. isert does not call iscsi_target_check_login_request() at all. Reject a login PDU whose declared DataSegmentLength exceeds what was received, in both paths that reach isert_rx_login_req(): isert_get_login_rx() for the first login PDU and isert_login_recv_done() for the ones after it. dlength ## CVSS-Vektor ``` CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H ``` | Metrik | Wert | Bewertung | |---|---|---| | AV Angriffsvektor | Netzwerk | bad | | AC Komplexität | Gering | bad | | PR Privilegien | Keine | bad | | UI Interaktion | Keine | bad | | S Scope | Unverändert | good | | C Vertraulichkeit | Hoch | bad | | I Integrität | Keine | good | | A Verfügbarkeit | Hoch | bad | ## Patch verfügbar (OSV) - Kernel ≥ 5.10.270 - Kernel ≥ 5.15.221 - Kernel ≥ 6.1.188 - Kernel ≥ 6.6.157 - Kernel ≥ 6.12.110 - Kernel ≥ 6.18.52 - Kernel ≥ 7.2.6 ## Referenzen - - - - - - - - --- _Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-90413) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_