Integer Underflow Vulnerability in libsmb2 Affecting SMB Servers
CVE-2026-110714

7.1HIGH

Key Information:

Vendor

Sahlberg

Status
Libsmb2
Vendor
CVE Published:
14 October 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-110714?

The libsmb2 library, specifically versions up to and including 6.2, contains an integer underflow vulnerability in its decode_acl function. This flaw allows malicious SMB servers to craft specific security descriptors that trigger heap out-of-bounds reads. By sending an AclSize value below 8 in a QUERY_INFO reply, an attacker can bypass Access Control Entry (ACE) bounds checks, potentially causing a crash of the client application. This vulnerability poses a significant risk, especially in environments where SMB services are used, as it enables attackers to exploit improperly handled data, leading to service interruptions and potential data exposure.

Affected Version(s)

libsmb2 0 <= 6.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-110714 - Proof of Concept

References

https://hackmd.io/@haind-pwn/libsmb2-query-info-reply-oob...
technical-descriptionexploit
https://github.com/sahlberg/libsmb2/blob/d67e213a5c4e7e49...
technical-description
https://github.com/sahlberg/libsmb2/commit/523abe20be3207...
patch

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

韓佳翰
HaiND from the Post and Telecommunication Institute of Technology
.