How severe is CVE-2021-1252?

CVE-2021-1252 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-1252 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-1252?

CVE-2021-1252 primarily affects Clamav. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-1252?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-1252 published?

CVE-2021-1252 was published on 2021-04-08 and last updated on 2026-06-17.

CVE-2021-1252

CVE-2021-1252 is a high-severity vulnerability in Clamav with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-835.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Clamav
Published: 2021-04-08
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-1252?: 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.
How severe is CVE-2021-1252?: CVE-2021-1252 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-1252 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1252?: CVE-2021-1252 primarily affects Clamav. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-1252?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-1252 published?: CVE-2021-1252 was published on 2021-04-08 and last updated on 2026-06-17.

References

https://blog.clamav.net/2021/04/clamav-01032-security-patch-release.html

Affected products (2)

cpe:2.3:a:clamav:clamav:0.103.0:*:*:*:*:*:*:*
cpe:2.3:a:clamav:clamav:0.103.1:*:*:*:*:*:*:*

More vulnerabilities in Clamav

CVE-2010-0098 — Critical (CVSS 10.0): ClamAV before 0.96 does not properly handle the (1) CAB and (2) 7z file formats, which allows remote attackers to…
CVE-2009-1372 — Critical (CVSS 10.0): Stack-based buffer overflow in the cli_url_canon function in libclamav/phishcheck.c in ClamAV before 0.95.1 allows…
CVE-2008-3914 — Critical (CVSS 10.0): Multiple unspecified vulnerabilities in ClamAV before 0.94 have unknown impact and attack vectors related to file…
CVE-2008-0728 — Critical (CVSS 10.0): The unmew11 function in libclamav/mew.c in libclamav in ClamAV before 0.92.1 has unknown impact and attack vectors that…
CVE-2006-1615 — Critical (CVSS 10.0): Multiple format string vulnerabilities in the logging code in Clam AntiVirus (ClamAV) before 0.88.1 might allow remote…
CVE-2025-20260 — Critical (CVSS 9.8): A vulnerability in the PDF scanning processes of ClamAV could allow an unauthenticated, remote attacker to cause a…

All CVEs affecting Clamav →

Other CWE-835 (Loop with Unreachable Exit Condition (Infinite Loop)) vulnerabilities

CVE-2026-24816 — Critical (CVSS 10.0): Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in datavane tis…
CVE-2018-20784 — Critical (CVSS 9.8): In the Linux kernel before 4.20.2, kernel/sched/fair.c mishandles leaf cfs_rq's, which allows attackers to cause a…
CVE-2017-12997 — Critical (CVSS 9.8): The LLDP parser in tcpdump before 4.9.2 could enter an infinite loop due to a bug in…
CVE-2017-12995 — Critical (CVSS 9.8): The DNS parser in tcpdump before 4.9.2 could enter an infinite loop due to a bug in print-domain.c:ns_print().
CVE-2017-12990 — Critical (CVSS 9.8): The ISAKMP parser in tcpdump before 4.9.2 could enter an infinite loop due to bugs in print-isakmp.c, several functions.
CVE-2026-31448 — Critical (CVSS 9.4): In the Linux kernel, the following vulnerability has been resolved: ext4: avoid infinite loops caused by residual…

Browse all CWE-835 (Loop with Unreachable Exit Condition (Infinite Loop)) vulnerabilities →