EUVD-2026-80617
GHSA-22qm-w4f2-g533
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local bsg+io_uring access (AV:L, PR:L); winning the TOCTOU race window requires a concurrent thread so AC:H; attacker-controlled heap overflow yields full C/I/A impact.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
Lifecycle Timeline
5DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
scsi: bsg: Fix TOCTOU in io_uring passthrough command setup
scsi_bsg_uring_cmd() reads bsg_uring_cmd from the shared mmap'd SQE. Userspace can change a field after we check it and before we use it. request_len is the sharp case: it can grow past sizeof(scmd->cmnd) after the bound check and overflow scmd->cmnd in copy_from_user().
READ_ONCE() the SQE fields we check or use into locals before use.
AnalysisAI
Local privilege escalation in the Linux kernel's SCSI bsg io_uring passthrough path (bsg_uring_cmd) allows an authenticated low-privileged local user (PR:L) to corrupt kernel memory via an out-of-bounds write, potentially escalating privileges or crashing the host. The handler validates fields read directly out of the user-shared, mmap'd io_uring SQE, so a racing thread can enlarge request_len after the bound check but before copy_from_user(), overflowing the fixed-size scmd->cmnd buffer inside the kernel. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Requires local access to a SCSI bsg device node (/dev/bsg/*) exposed to the attacker and a kernel built with io_uring passthrough support (Linux 7.1 affected). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is one of the more genuinely serious CVEs in the current Linux kernel batch, and the vendor CVSS of 7.8 (AV:L/AC:L/PR:L/C:H/I:H/A:H) is largely defensible rather than the routine over-scoring seen in sibling DoS-only bugs. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patches are available: update to Linux 7.2.5 (stable) or 7.3-rc2 and later, which contain the READ_ONCE() hardening commits f033530105aa73d82c121d54b57f358e4865d2f4 and 4b3c5965fca99f62d31c963294bd5b23cc488e97 (https://git.kernel.org/stable/c/f033530105aa73d82c121d54b57f358e4865d2f4 and https://git.kernel.org/stable/c/4b3c5965fca99f62d31c963294bd5b23cc488e97); distributions that backported bsg io_uring passthrough must apply the equivalent downstream backport since their package version may not reflect upstream numbering. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify every Linux host running a kernel built with bsg io_uring passthrough support (EUVD places Linux 7.1 in the affected commit range) and confirm which of them actually expose a /dev/bsg device node and to whom; restrict /dev/bsg permissions to root or a tightly scoped trusted group and ensure only users with a genuine need for SCSI passthrough can open it. …
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Same technique Buffer Overflow
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External POC / Exploit Code
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