Security readout for executives and security teams
Plain-English summary
This flaw can let a remote unauthenticated sender crash ClamAV’s scanning process by sending a crafted email. The main business risk is loss of malware scanning availability on email gateways or systems that rely on ClamAV, potentially delaying mail flow or reducing security coverage.
Executive priority
Treat as a high-priority availability issue for email security infrastructure. Patch exposed scanners promptly, especially where ClamAV failure could interrupt mail handling or reduce malware detection.
Technical view
CVE-2021-1405 affects ClamAV 0.103.1 and prior. The provided description cites improper variable initialization in the email parsing module, leading to a NULL pointer read and scanning process crash. CVSS is 7.5, availability-only impact. The title references PDF parsing, but the provided description emphasizes email parsing.
Likely exposure
Exposure is most likely where ClamAV scans inbound email, attachments, or files from untrusted sources, especially mail gateways and automated scanning pipelines running 0.103.1 or older.
Exploitation context
The bundle describes remote unauthenticated exploitation through a crafted email. CISA KEV is false, and the provided sources do not establish active exploitation in the wild.
Researcher notes
Evidence supports a denial-of-service condition, not confidentiality or integrity compromise. The source bundle does not provide exploit details, active exploitation evidence, or alternative mitigations beyond vendor and distribution security updates.
Mitigation direction
- Upgrade ClamAV to 0.103.2 or later.
- Apply Debian, Gentoo, or vendor security packages where applicable.
- Prioritize email gateways and automated scanning services.
- Monitor for repeated ClamAV scanner crashes or mail processing failures.
- Check vendor guidance for unsupported or pinned deployments.
Validation and detection
- Confirm installed ClamAV versions on all scanning hosts.
- Verify package changelogs reference CVE-2021-1405 or the 0.103.2 fix.
- Review logs for scanner crashes around email processing.
- Confirm scanning services restart cleanly after patching.
- Test normal mail and attachment scanning after upgrade.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-1405 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://blog.clamav.net/2021/04/clamav-01032-security-patch-release.htmlCVE reference · vendor-advisory, x_refsource_CISCO
- [debian-lts-announce] 20210414 [SECURITY] [DLA 2626-1] clamav security updateCVE reference · mailing-list, x_refsource_MLIST
- GLSA-202104-07CVE reference · vendor-advisory, x_refsource_GENTOO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.