// For flags

CVE-2021-1252

Clam AntiVirus (ClamAV) Excel XLM Parser Denial of Service Vulnerability

Severity Score

7.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Attend
*SSVC
Descriptions

A 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.

Una vulnerabilidad en el módulo de análisis de macros Excel XLM en Clam AntiVirus (ClamAV) versiones 0.103.0 y 0.103.1 del software, podría permitir a un atacante remoto no autenticado causar una condición de denegación de servicio en un dispositivo afectado. La vulnerabilidad es debido a un manejo inapropiado de errores que puede resultar en un bucle infinito. Un atacante podría explotar esta vulnerabilidad mediante el envío de un archivo de Excel diseñado a un dispositivo afectado. Una explotación podría permitir al atacante causar que el proceso de escaneo de ClamAV se bloquee, resultando en una condición de denegación de servicio

It was discovered that ClamAV incorrectly handled parsing Excel documents. A remote attacker could possibly use this issue to cause ClamAV to hang, resulting in a denial of service. It was discovered that ClamAV incorrectly handled parsing PDF documents. A remote attacker could possibly use this issue to cause ClamAV to crash, resulting in a denial of service. It was discovered that ClamAV incorrectly handled parsing email. A remote attacker could possibly use this issue to cause ClamAV to crash, resulting in a denial of service. Various other issues were also addressed.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete
* Common Vulnerability Scoring System
SSVC
  • Decision:Attend
Exploitation
None
Automatable
Yes
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2020-11-13 CVE Reserved
  • 2021-04-07 CVE Published
  • 2024-11-08 CVE Updated
  • 2025-03-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-20: Improper Input Validation
  • CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Clamav
Search vendor "Clamav"
Clamav
Search vendor "Clamav" for product "Clamav"
0.103.0
Search vendor "Clamav" for product "Clamav" and version "0.103.0"
-
Affected
Clamav
Search vendor "Clamav"
Clamav
Search vendor "Clamav" for product "Clamav"
0.103.1
Search vendor "Clamav" for product "Clamav" and version "0.103.1"
-
Affected