xlnt-community xlnt Encrypted XLSX File base64.cpp decode_base64 off-by-one

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-2703
StatePUBLISHED
AssignerVulDB
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-02-19 07:17:49 UTC
Updated2026-04-29 01:00:01 UTC
DescriptionA weakness has been identified in xlnt-community xlnt up to 1.6.1. Impacted is the function xlnt::detail::decode_base64 of the file source/detail/cryptography/base64.cpp of the component Encrypted XLSX File Parser. Executing a manipulation can lead to off-by-one. The attack requires local access. The exploit has been made available to the public and could be used for attacks. This patch is called f2d7bf494e5c52706843cf7eb9892821bffb0734. Applying a patch is advised to resolve this issue.

Risk And Classification

Primary CVSS: v4.0 1.9 LOW from [email protected]

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-189 | CWE-193 | CWE-193 Off-by-One | CWE-189 Numeric Error

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary1.9LOWCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/C...
4.0CNADECLARED4.8MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1[email protected]Secondary3.3LOWCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED3.3LOWCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
3.0CNADECLARED3.3LOWCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
2.0[email protected]Secondary1.7AV:L/AC:L/Au:S/C:N/I:N/A:P
2.0CNADECLARED1.7AV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:OF/RC:C

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Xlnt-community Xlnt All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Xlnt-community Xlnt affected 1.6.0 Not specified
CNA Xlnt-community Xlnt affected 1.6.1 Not specified

References

ReferenceSourceLinkTags
github.com/oneafter/0128/blob/main/xl1/repro [email protected] github.com Exploit
github.com/xlnt-community/xlnt/commit/f2d7bf494e5c52706843cf7eb9892821bf... [email protected] github.com Patch
vuldb.com [email protected] vuldb.com Third Party Advisory, VDB Entry
github.com/xlnt-community/xlnt/issues/137 [email protected] github.com Exploit, Issue Tracking, Vendor Advisory
github.com/xlnt-community/xlnt [email protected] github.com Product
vuldb.com [email protected] vuldb.com Third Party Advisory, VDB Entry
vuldb.com [email protected] vuldb.com Permissions Required, VDB Entry
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Oneafter (VulDB User) (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-02-18T00:00:00.000ZAdvisory disclosed
CNA2026-02-18T01:00:00.000ZVulDB entry created
CNA2026-02-18T19:04:11.000ZVulDB entry last update

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