Cyber Resilience

CVE-2026-43185

CriticalDDoS

Published: 06 May 2026

Published
06 May 2026
Modified
11 May 2026
KEV Added
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Patch
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CVSS Score v3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0062 45.4th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-43185 is a critical-severity Uncontrolled Recursion (CWE-674) vulnerability in Linux Linux Kernel. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 45.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix signededness bug in smb_direct_prepare_negotiation() smb_direct_prepare_negotiation() casts an unsigned __u32 value from sp->max_recv_size and req->preferred_send_size to a signed int before computing min_t(int, ...). A maliciously provided preferred_send_size of 0x80000000…

more

will return as smaller than max_recv_size, and then be used to set the maximum allowed alowed receive size for the next message. By sending a second message with a large value (>1420 bytes) the attacker can then achieve a heap buffer overflow. This fix replaces min_t(int, ...) with min_t(u32)

CWE(s)
CWE-674

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Why these techniques?

Remote heap buffer overflow in ksmbd (public SMB service) directly enables server-side RCE via crafted SMB Direct negotiation packets.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

linux
linux kernel
7.0 · 5.15 — 6.18.16 · 6.19 — 6.19.6

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CP-7 Alternate Processing Site
addresses: CWE-674

Supports resumption at alternate site when uncontrolled recursion causes primary site failure or crash.

SC-5 Denial-of-service Protection
addresses: CWE-674

Prevents uncontrolled recursion that exhausts stack or CPU resources.

References