CVE-2021-1252
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 · uneditedA vulnerability in the Excel XLM macro parsing module in Clam AntiVirus (ClamAV) Software versions 0.103.0 and 0.103.1 could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. The vulnerability is due to improper error handling that may result in an infinite loop. An attacker could exploit this vulnerability by sending a crafted Excel file to an affected device. An exploit could allow the attacker to cause the ClamAV scanning process hang, resulting in a denial of service condition.
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 confidenceA vulnerability in ClamAV's Excel XLM macro parsing module (versions 0.103.0 and 0.103.1) allows an unauthenticated remote attacker to cause a denial of service by sending a crafted Excel file. The vulnerability stems from improper error handling that triggers an infinite loop, causing the ClamAV scanning process to hang.
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= 0.103.0= 0.103.1CVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 checksWork through these to decide whether this CVE applies to you.
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Check installed ClamAV versionRun `clamd --version` or `clamscan --version` to display the ClamAV engine versionAffected if The displayed version is 0.103.0 or 0.103.1
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Verify Excel file scanning is activeInspect the ClamAV configuration file (typically /etc/clamd.conf or /etc/clamav/clamd.conf) for directives that enable Excel file parsing, such as checking if the bytecode interpreter is enabled and reviewing logs for recent Excel file scansAffected if Excel file scanning is enabled and the ClamAV version is 0.103.0 or 0.103.1
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Confirm XLM macro parsing is enabledReview clamd.conf for any XLM-related settings or macro parsing enablement for Excel files; also check if the ClamAV database includes the excel-xlm* signaturesAffected if XLM macro parsing is active and the version is 0.103.0 or 0.103.1
You are affected if ClamAV version 0.103.0 or 0.103.1 is installed AND Excel files with XLM macros are being scanned.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataUpgrade ClamAV to version 0.103.2 or later, which contains the fix for this vulnerability. Alternatively, consider disabling Excel file scanning or XLM macro parsing as a temporary workaround if immediate upgrading is not feasible.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1252 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-1252 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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