CVE-2026-3665Public exploit

Application crash via malformed document relationships

Published Mar 7, 2026 · Updated Mar 7, 2026

Null pointer dereference in xlnt 1.6.0 and 1.6.1 allows local users to crash an application by loading a malformed XLSX file. The read_office_document function searches document relationships with std::find_if, whose predicate constructs strings from missing or invalid relationship data and dereferences a null pointer. Reachability requires a local low-privileged user to make a consuming application parse the file; the demonstrated consequence is process termination, with no reported data disclosure or modification.

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

What happened

Null pointer dereference in xlnt 1.6.0 and 1.6.1 allows local users to crash an application by loading a malformed XLSX file. The read_office_document function searches document relationships with std::find_if, whose predicate constructs strings from missing or invalid relationship data and dereferences a null pointer. Reachability requires a local low-privileged user to make a consuming application parse the file; the demonstrated consequence is process termination, with no reported data disclosure or modification.

The record

CVE
CVE-2026-3665
Published
Mar 7, 2026
Updated
Mar 7, 2026
Vendor
xlnt Community
Product
xlnt
Classifications
CWE-476, CWE-404, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 7, 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

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
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

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
CWE-404Improper Resource Shutdown or Release
T1499.004Application or System Exploitation

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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