---
id: CVE-2026-78002
title: A flaw was found in rsyslog
summary: >-
  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 …
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-131
vendor: Red Hat
product: rsyslog
affected:
  - rsyslog (all versions)
  - rsyslog (all versions)
  - rhui5/haproxy-rhel9 (all versions)
  - rsyslog (all versions)
  - rsyslog7
  - rsyslog (all versions)
  - rsyslog (all versions)
patched:
  - enterprise_linux_appstream_v_10
  - enterprise_linux_appstream_v_9
published: '2026-08-27'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T22:17:01.573'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78002'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:69540'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:69541'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:71603'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-78002'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2521135'
    label: secalert@redhat.com
  - url: 'https://github.com/rsyslog/rsyslog/security/advisories/GHSA-g72f-gc6v-f2w3'
    label: secalert@redhat.com
  - url: 'http://www.openwall.com/lists/oss-security/2026/08/29/1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-78002.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-78002'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78002'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-08-27T18:29:21.461066Z'
epss: 0.00691
epssPercentile: 0.50734
ingestedAt: '2026-08-29T23:43:55.086Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · updated 2026-09-22 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-78002.json)
- **RHSA-2026:69541** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69541)
- **RHSA-2026:69540** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-09-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:69540)