CVE-2026-2703Public exploit

Process crash via Base64 output-size miscalculation

Published Feb 19, 2026 · Updated Feb 19, 2026

Heap-buffer overflow in xlnt 1.6.0 and 1.6.1 allows local users to crash consuming processes via a malformed encrypted XLSX file. decode_base64 preallocates a vector from the encoded length and padding count, then its final-byte loop writes one decoded byte past that allocation. Exploitation requires a local user to make an xlnt-linked process load the crafted file; the demonstrated consequence is a process crash.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Heap-buffer overflow in xlnt 1.6.0 and 1.6.1 allows local users to crash consuming processes via a malformed encrypted XLSX file. decode_base64 preallocates a vector from the encoded length and padding count, then its final-byte loop writes one decoded byte past that allocation. Exploitation requires a local user to make an xlnt-linked process load the crafted file; the demonstrated consequence is a process crash.

The record

CVE
CVE-2026-2703
Published
Feb 19, 2026
Updated
Feb 19, 2026
Vendor
xlnt Community
Product
xlnt
Classifications
CWE-189, CWE-193
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.6.0
  2. Affected versionversion=1.6.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

xlnt Community · xlntversion=1.6.0; version=1.6.1

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
1.7VulDBAV:L/AC:L/Au:S/C:N/I:N/A:P
3.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
1.9VulDBCVSS: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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-189Numeric Errors
CWE-193Off-by-one Error

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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