Out-of-Bounds Read in xlnt XLSX File Parser by xlnt-community
CVE-2026-3663

4.8MEDIUM

Key Information:

Vendor

Xlnt-community

Status
Xlnt
Vendor
CVE Published:
7 March 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-3663?

A local access vulnerability exists in the xlnt XLSX File Parser, specifically within the function xlnt::detail::compound_document_istreambuf::xsgetn. This flaw can lead to an out-of-bounds read when manipulated, potentially exposing sensitive information. The issue affects versions of xlnt up to 1.6.1 and has been publicly disclosed, making it critical for users to update to the patched version identified as patch 147 to mitigate any risks. It is advisable for users to implement the patch promptly to address this vulnerability.

Affected Version(s)

xlnt 1.6.0

xlnt 1.6.1

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-2026-3663 - Proof of Concept

References

https://vuldb.com/?id.349552
vdb-entrytechnical-description
https://vuldb.com/?ctiid.349552
signaturepermissions-required
https://vuldb.com/?submit.764644
third-party-advisory

CVSS V4

Score:
4.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
Low
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Oneafter (VulDB User)
.