CVE-2026-2703

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

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.

Affected

xlnt-community · xlnt

CVSS v4.0 VULDB

1.9 LOWCVSS: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 NVD

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

CVSS v3.1 VULDB

3.3 LOWCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CVSS v2.0 VULDB

1.7 LOWAV:L/AC:L/Au:S/C:N/I:N/A:P

EPSS

0.22% chance of exploitation in the next 30 days, 11th percentile

Published

2026-02-19

Updated

2026-02-24

Proof-of-concept exploits (1)

• oneafter/0128/blob/main/xl1/repro0★ · 2026-01-29

Security advisories

• xlnt-community/xlnt/issues/137
• https://vuldb.com/?id.346649
• https://vuldb.com/?submit.754377

References

• CVE Record
• NVD entry