CVE-2021-41830Public exploitNetwork attack vector

Content spoofing and macro execution via certificate doubling

Published Oct 11, 2021 · Updated Aug 4, 2024

Improper signature verification in Apache OpenOffice 4.1.10 and earlier allows attackers to forge trusted ODF documents and macros. During XML-signature validation, separate X.509 certificates can satisfy cryptographic verification and trust validation, so no single certificate must pass both checks. An attacker who obtains a signed ODF file can alter its content or replace protected macros while the application continues to display the signature as valid and trusted.

CVSS severity7.5
High
EPSS probability1.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Apache OpenOffice 4.1.10 and earlier allows attackers to forge trusted ODF documents and macros. During XML-signature validation, separate X.509 certificates can satisfy cryptographic verification and trust validation, so no single certificate must pass both checks. An attacker who obtains a signed ODF file can alter its content or replace protected macros while the application continues to display the signature as valid and trusted.

The record

CVE
CVE-2021-41830
Published
Oct 11, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache OpenOffice
Classifications
CWE-347, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=Apache OpenOffice <=4.1.10
  2. Affected versionversion=OpenOffice.org <=3.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache OpenOfficeversion=Apache OpenOffice <=4.1.10; version=OpenOffice.org <=3.4

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1204.002User Execution: Malicious File

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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