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Fencer Vulns
high 7.5

CVE-2021-1252 json

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

published 2021-04-08 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-6719

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.5%
EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

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.

Patch / fix

  • clamav Debian 14, Debian 13, Debian 12 0.103.2+dfsg-1

debian advisories DEBIAN-CVE-2021-1252

  • clamav Ubuntu 16.04 LTS 0.103.2+dfsg-0ubuntu0.16.04.1
  • clamav Ubuntu 18.04 LTS 0.103.2+dfsg-0ubuntu0.18.04.1
  • clamav Ubuntu 20.04 LTS 0.103.2+dfsg-0ubuntu0.20.04.1
  • clamav Ubuntu Pro 14.04 LTS 0.103.2+dfsg-0ubuntu0.14.04.1+esm1

ubuntu advisories UBUNTU-CVE-2021-1252

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • clamav SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +11 more 0.103.2-3.26.1
  • clamav SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES 12 SP4-LTSS +8 more 0.103.2-33.35.1
  • clamav SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 0.103.2-0.20.35.1
  • clamav SLES for SAP 12 SP5, SLES 12 SP5 0.103.2-3.6.1

suse advisories SUSE-SU-2021:1190-1SUSE-SU-2021:1189-1SUSE-SU-2021:14692-1SUSE-SU-2021:1174-1

  • clamav openSUSE Tumbleweed 0.103.3-1.4
  • clamav openSUSE Leap 15.2 0.103.2-lp152.6.6.1

opensuse advisories openSUSE-SU-2024:10685-1openSUSE-SU-2021:0555-1

  • clamav Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 0.103.2-r0

alpine advisories ALPINE-CVE-2021-1252

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • clamav Arch Linux 0.103.2-1

arch linux advisories AVG-1787

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-1252 updated cvss 7.5

clamav: denial of service in Excel XLM macro parsing module

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

2.52% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 7.8 AV:N/AC:L/Au:N/C:N/I:N/A:C

Affected products

  • Cisco ClamAV

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.