CVE-2026-78002 Rsyslog: rsyslog: denial of service via heap buffer overflow in rainerscript replace() function
An unauthenticated remote attacker can cause a denial of service in rsyslog by triggering a heap buffer overflow via crafted syslog messages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-78002?
CVE-2026-78002 is a high-severity memory corruption vulnerability in Red Hat Enterprise Linux 10, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-131
Which versions are affected by CVE-2026-78002?
Linux distribution packages (40)
rsyslog AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-crypto AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-doc AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-elasticsearch AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-gnutls AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-gssapi AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-kafka AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mmaudit AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mmfields AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mmjsonparse AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mmkubernetes AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mmnormalize AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mmsnmptrapd AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-mysql AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-omamqp1 AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-openssl AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-pgsql AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-relp AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-snmp AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog-udpspoof AlmaLinux:10 | All versions | 8.2510.0-5.el10_2.2 |
rsyslog AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-crypto AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-doc AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-elasticsearch AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-gnutls AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-gssapi AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-kafka AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-logrotate AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mmaudit AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mmfields AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mmjsonparse AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mmkubernetes AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mmnormalize AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mmsnmptrapd AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-mysql AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-omamqp1 AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-openssl AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-pgsql AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-relp AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
rsyslog-snmp AlmaLinux:9 | All versions | 8.2510.0-2.el9_8.2 |
How do I fix CVE-2026-78002?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-78002 being exploited?
There is no known exploitation of CVE-2026-78002 in the wild and no public exploit code.
Sources
Also known as ALSA-2026:69540, ALSA-2026:69541, AZL-98400, CLSA-2026-1790795134, CLSA-2026-1790809774, CLSA-2026-1791277281 and 19 more.