Rsyslog: rsyslog: denial of service via heap buffer overflow in rainerscript replace() function
Summary
| CVE | CVE-2026-78002 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-27 17:20:29 UTC |
| Updated | 2026-08-29 23:17:23 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.006060000 probability, percentile 0.462900000 (date 2026-08-29)
Problem Types: CWE-131 | CWE-131 Incorrect Calculation of Buffer Size
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.openwall.com/lists/oss-security/2026/08/29/1 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| github.com/rsyslog/rsyslog/security/advisories/GHSA-g72f-gc6v-f2w3 | [email protected] | github.com | |
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-78002 | [email protected] | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-08-21T19:28:07.933Z | Reported to Red Hat. |
| CNA | 2026-08-26T00:00:00.000Z | Made public. |
Workarounds
CNA: 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.