# 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. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 27 Aug 2026 - **Updated:** 26 Oct 2026 - **Also known as:** ALSA-2026:69540, ALSA-2026:69541, AZL-98400, CLSA-2026-1790795134, CLSA-2026-1790809774, CLSA-2026-1791277281, CLSA-2026-1791277470, CLSA-2026-1791371082, CLSA-2026-1791918528, CLSA-2026-1791954698, CLSA-2026-1791960930, CLSA-2026-1792399166, DEBIAN-CVE-2026-78002, OESA-2026-3838, OESA-2026-3839, OESA-2026-3840, OESA-2026-3841, OESA-2026-3934, RHSA-2026:69540, RHSA-2026:69541, RHSA-2026:81321, RLSA-2026:69540, RLSA-2026:69541, UBUNTU-CVE-2026-78002, USN-8786-1 ## 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 (Incorrect Calculation of Buffer Size) ## Which versions are affected by CVE-2026-78002? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `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. ## Is CVE-2026-78002 being exploited? There is no known exploitation of CVE-2026-78002 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-78002 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2026-78002 in the wild and no public exploit code. Affected product: Red Hat Enterprise Linux 10. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-78002/ (Markdown: https://insights.sbomify.com/CVE-2026-78002/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78002 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78002 - OSV: https://osv.dev/vulnerability/CVE-2026-78002 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-78002/ Summaries are generated and may contain mistakes; the official description above is the record.