dbcve.org
FedoraOperating system · Fedoraproject

CVE-2021-25636

HIGH · 7.5 CVSS v3.1 Published 2022-02-24
Fix available
A fix is available. Upgrade to 7.2.5 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
LibreOffice supports digital signatures of ODF documents and macros within documents, presenting visual aids that no alteration of the document occurred since the last signing and that the signature is valid. An Improper Certificate Validation vulnerability in LibreOffice allowed an attacker to create a digitally signed ODF document, by manipulating the documentsignatures.xml or macrosignatures.xml stream within the document to contain both "X509Data" and "KeyValue" children of the "KeyInfo" tag, which when opened caused LibreOffice to verify using the "KeyValue" but to report verification with the unrelated "X509Data" value. This issue affects: The Document Foundation LibreOffice 7.2 versions prior to 7.2.5.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

LibreOffice improperly validates digital signatures in ODF documents by using the KeyValue element for cryptographic verification but displaying verification status based on the unrelated X509Data element. This allows attackers to craft documents appearing legitimately signed by embedding both elements and exploiting the mismatch between verification and reporting logic.

MitigationUpdate LibreOffice to version 7.2.5 or later which contains the fix for this improper certificate validation vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 34
LibreofficeApplication
Affected:>= 7.2.0, < 7.2.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed LibreOffice version
    Open LibreOffice and go to Help > About LibreOffice, or run 'libreoffice --version' from command line
    Affected if Version is 7.2.0, 7.2.1, 7.2.2, 7.2.3, or 7.2.4 (versions 7.2.0 through 7.2.4 are vulnerable)
  2. Confirm operating system is Fedora 34
    Run 'cat /etc/fedora-release' or 'cat /etc/os-release' to identify the OS version
    Affected if Running Fedora 34 with the default LibreOffice package
  3. Identify if ODF document signature verification is in use
    Open an ODF document (.odt, .ods, .odp) and check if digital signatures are present via File > Properties > Digital Signatures
    Affected if Regularly opening ODF documents that may contain digital signatures from untrusted sources

You are affected if LibreOffice version is 7.2.0 through 7.2.4, or if using Fedora 34 with its packaged LibreOffice, and you open ODF documents containing digital signatures.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 7.2.5 or later
Fixed in 7.2.5
Interim mitigation

Update LibreOffice to version 7.2.5 or later which contains the fix for this improper certificate validation vulnerability.

Recommended fix High confidence

LibreOffice 7.2.5 or later (recommended: latest stable 7.2.x or 7.3.x release)

  1. Check current LibreOffice version by opening LibreOffice and going to Help > About LibreOffice, or run: libreoffice --version
  2. Update LibreOffice to version 7.2.5 or later (or latest available 7.2.x/7.3.x stable release) using your system's package manager
  3. For Fedora: Run 'sudo dnf update libreoffice-*' to install the fixed package
  4. Verify the fix by checking the updated version: libreoffice --version
  5. After updating, digitally signed documents will properly verify both X509Data and KeyValue components of the signature
Caveat Minor - this is a security fix upgrade within the same major.minor branch; no major functionality changes expected for typical users

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fedora Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-25636 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data