---
cve: "CVE-2026-74556"
severity: "CRITICAL"
cvss: 9.8
epss: "40%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-08-15 13:18:01"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-03T00:59:58+02:00"
---

# CVE-2026-74556

> 9.8 CRITICAL

## Beschreibung

In the Linux kernel, the following vulnerability has been resolved:

scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer

iscsi_tcp_hdr_dissect() receives the data segment of several PDU types
into the fixed-size conn->data buffer, which is allocated for
ISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes.  For the LOGIN_RSP, TEXT_RSP,
REJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU
whose DataSegmentLength exceeds that buffer.

The SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its
data segment (sense/response data) into conn->data via
iscsi_tcp_data_recv_prep(), but it does so without the same check.  The
only upstream bound on in.datalen is conn->max_recv_dlength, the
initiator's advertised MaxRecvDataSegmentLength, which is commonly
negotiated well above 8192 (open-iscsi defaults to 262144).  A target
that returns a SCSI Response with a DataSegmentLength between 8193 and
max_recv_dlength therefore overflows the 8192-byte conn->data buffer.

Once the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly
like those responses: bound the data segment, receive it into conn->data
when present, and otherwise complete the PDU with no data.  Fold the
opcode into that case group rather than duplicating the check.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.10.265
- Kernel ≥ 5.15.216
- Kernel ≥ 6.1.183
- Kernel ≥ 6.6.151
- Kernel ≥ 6.12.103
- Kernel ≥ 6.18.44
- Kernel ≥ 7.1.8

## Referenzen

- <https://git.kernel.org/stable/c/a51812842084fd390590ab8dc0431f10c73ddc56>
- <https://git.kernel.org/stable/c/a8f94cc9f0e5759252551be3a172960c57f21f54>
- <https://git.kernel.org/stable/c/f1a3a51fc5dba0e99532379665069f1700da6b44>
- <https://git.kernel.org/stable/c/c97b5265cc47775f77fd2a23d6bde0426997b233>
- <https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b>
- <https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7>
- <https://git.kernel.org/stable/c/b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676>
- <https://git.kernel.org/stable/c/c1dea15f819cded9b3faf58f8bec72323568b6e6>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74556) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_