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Description

A 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.

PUBLISHED Reserved 2026-02-18 | Published 2026-02-19 | Updated 2026-02-24 | Assigner VulDB




MEDIUM: 4.8CVSS: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
LOW: 3.3CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
LOW: 3.3CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
1.7AV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:OF/RC:C

Problem types

Off-by-One

Numeric Error

Product status

1.6.0
affected

1.6.1
affected

Timeline

2026-02-18:Advisory disclosed
2026-02-18:VulDB entry created
2026-02-18:VulDB entry last update

Credits

Oneafter (VulDB User) reporter

References

vuldb.com/?id.346649 (VDB-346649 | xlnt-community xlnt Encrypted XLSX File base64.cpp decode_base64 off-by-one) vdb-entry technical-description

vuldb.com/?ctiid.346649 (VDB-346649 | CTI Indicators (IOB, IOC, IOA)) signature permissions-required

vuldb.com/?submit.754377 (Submit #754377 | xlnt-community xlnt 5606f5b Heap-based Buffer Overflow) third-party-advisory

github.com/xlnt-community/xlnt/issues/137 issue-tracking

github.com/oneafter/0128/blob/main/xl1/repro exploit

github.com/...ommit/f2d7bf494e5c52706843cf7eb9892821bffb0734 patch

github.com/xlnt-community/xlnt/ product

cve.org (CVE-2026-2703)

nvd.nist.gov (CVE-2026-2703)

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