CVE-2021-28040

Name: CVE-2021-28040
Creator: NVD / NIST
Published: 2021-03-05T18:15:13.27+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.19%

Last modified Jun 17, 2026

CVE-2021-28040 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. An issue was discovered in OSSEC 3.6.0. An uncontrolled recursion vulnerability in os_xml.c occurs when a large number of opening and closing XML tags is used. EPSS estimates a 1.19% chance of exploitation in the next 30 days.

Description

An issue was discovered in OSSEC 3.6.0. An uncontrolled recursion vulnerability in os_xml.c occurs when a large number of opening and closing XML tags is used. Because recursion is used in _ReadElem without restriction, an attacker can trigger a segmentation fault once unmapped memory is reached.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.19%

64.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-674

Affected Software

Vendor	Product	Versions
Ossec	Ossec	3.6.0

References

https://github.com/ossec/ossec-hids/issues/1953Exploit, Issue Tracking, Third Party Advisory
https://github.com/ossec/ossec-hids/issues/1953Exploit, Issue Tracking, Third Party Advisory

Timeline

Published: Mar 5, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-28040?

How severe is CVE-2021-28040?

CVE-2021-28040 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.19% probability of exploitation in the next 30 days.

How do I fix CVE-2021-28040?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-28040?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST