CVE-2021-25636Network attack vector

Signing-identity spoofing via ambiguous KeyInfo children

Published Feb 22, 2022 · Updated Aug 3, 2024

Improper signature verification in LibreOffice 7.2 before 7.2.5 allows attackers to misrepresent an ODF document's signing identity. The XML-signature validators accept both X509Data and KeyValue under KeyInfo, verify with KeyValue, then display the unrelated X509Data certificate. A target must open the crafted ODF document; the result is a false trust indicator for the signer, not code execution or data disclosure.

CVSS severity7.5
High
EPSS probability0.95%
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 LibreOffice 7.2 before 7.2.5 allows attackers to misrepresent an ODF document's signing identity. The XML-signature validators accept both X509Data and KeyValue under KeyInfo, verify with KeyValue, then display the unrelated X509Data certificate. A target must open the crafted ODF document; the result is a false trust indicator for the signer, not code execution or data disclosure.

The record

CVE
CVE-2021-25636
Published
Feb 22, 2022
Updated
Aug 3, 2024
Vendor
The Document Foundation
Product
LibreOffice
Classifications
CWE-347, CWE-295, T1553.002, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=7.2 <7.2.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Document Foundation · LibreOfficeversion=7.2 <7.2.5

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST National Vulnerability DatabaseAV: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
CWE-295Improper Certificate Validation
T1553.002Subvert Trust Controls: Code Signing
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

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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