Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-08-26T00:00:00 rsyslog: rsyslog: Denial of service via heap buffer overflow in RainerScript replace() function 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CWE-131

A flaw was found in rsyslog. An unauthenticated remote attacker can trigger a heap buffer overflow in the RainerScript `replace()` function by sending specially crafted syslog messages. This vulnerability arises from an incorrect buffer size calculation during string replacement, causing memory corruption. Successful exploitation can lead to a denial of service (DoS) for the affected system.

A flaw was found in rsyslog. An unauthenticated remote attacker can trigger a heap buffer overflow in the RainerScript `replace()` function by sending specially crafted syslog messages. This vulnerability arises from an incorrect buffer size calculation during string replacement, causing memory corruption. Successful exploitation can lead to a denial of service (DoS) for the affected system.

This Important flaw in rsyslog allows an unauthenticated remote attacker to trigger a heap buffer overflow, leading to a denial of service. The vulnerability occurs when processing specially crafted syslog messages containing specific RainerScript `replace()` function calls. Red Hat Enterprise Linux systems configured to receive remote syslog messages are susceptible to this issue, potentially impacting logging availability. To mitigate this vulnerability, restrict network access to the rsyslog service to only trusted hosts. This can be achieved by configuring firewall rules to limit incoming connections to UDP and TCP port 514. Alternatively, if remote syslog reception is not required, disable the `imudp` and `imtcp` modules in the `/etc/rsyslog.conf` configuration file. After modifying the rsyslog configuration or firewall rules, the rsyslog service or firewall service must be restarted for the changes to take effect. Red Hat Enterprise Linux 10 Affected rsyslog Red Hat Enterprise Linux 6 Affected rsyslog Red Hat Enterprise Linux 6 Affected rsyslog7 Red Hat Enterprise Linux 7 Affected rsyslog Red Hat Enterprise Linux 8 Affected rsyslog Red Hat Enterprise Linux 9 Affected rhel9/rsyslog Red Hat Enterprise Linux 9 Affected rsyslog https://www.cve.org/CVERecord?id=CVE-2026-78002 https://nvd.nist.gov/vuln/detail/CVE-2026-78002 https://github.com/rsyslog/rsyslog/security/advisories/GHSA-g72f-gc6v-f2w3