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.

ubuntu_linux USN-8786-1: Ubuntu 16.04 LTS / Ubuntu 18.04 LTS / Ubuntu 20.04 LTS / Ubuntu 22.04 LTS / Ubuntu 24.04 LTS / Ubuntu 26.04 LTS / Ubuntu Pro Realtime 22.04 LTS / Ubuntu Pro Realtime 24.04 LTS : rsyslog vulnerability (USN-8786-1)

The remote AlmaLinux 10 host has packages installed that are affected by a vulnerability as referenced in the ALSA-2026:69541 advisory.

    * rsyslog: rsyslog: Denial of service via heap buffer overflow in RainerScript replace() function     (CVE-2026-78002)

Tenable has extracted the preceding description block directly from the AlmaLinux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 10 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2026-69541 advisory.

    [8.2510.0-5.2]
    - Fix CVE-2026-78002: heap buffer overflow in RainerScript replace() function       Resolves: RHEL-246633

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote AlmaLinux 9 host has packages installed that are affected by a vulnerability as referenced in the ALSA-2026:69540 advisory.

    * rsyslog: rsyslog: Denial of service via heap buffer overflow in RainerScript replace() function     (CVE-2026-78002)

Tenable has extracted the preceding description block directly from the AlmaLinux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2026:69540 advisory.

    The rsyslog packages provide an enhanced, multi-threaded syslog daemon. It supports MySQL, syslog/TCP, RFC     3195, permitted sender lists, filtering on any message part, and fine-grained control over output format.

    Security Fix(es):

    * rsyslog: rsyslog: Denial of service via heap buffer overflow in RainerScript replace() function     (CVE-2026-78002)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2026:69541 advisory.

    The rsyslog packages provide an enhanced, multi-threaded syslog daemon. It supports MySQL, syslog/TCP, RFC     3195, permitted sender lists, filtering on any message part, and fine-grained control over output format.

    Security Fix(es):

    * rsyslog: rsyslog: Denial of service via heap buffer overflow in RainerScript replace() function     (CVE-2026-78002)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The version of Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the TSSA-2026:1017 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-78002:
    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.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The version of rsyslog installed on the remote host is prior to 8.24.0-57. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3904 advisory.

    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. (CVE-2026-78002)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-2133 advisory.

    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. (CVE-2026-78002)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-78002)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
348817	AlmaLinux 10 : rsyslog (ALSA-2026:69541)	Nessus	Alma Linux Local Security Checks	Local	high
348772	Oracle Linux 10 : rsyslog (ELSA-2026-69541)	Nessus	Oracle Linux Local Security Checks	Local	high
348738	AlmaLinux 9 : rsyslog (ALSA-2026:69540)	Nessus	Alma Linux Local Security Checks	Local	high
348718	RHEL 9 : rsyslog (RHSA-2026:69540)	Nessus	Red Hat Local Security Checks	Local	high
348686	RHEL 10 : rsyslog (RHSA-2026:69541)	Nessus	Red Hat Local Security Checks	Local	high
348668	TencentOS Server 4: rsyslog (TSSA-2026:1017)	Nessus	Tencent Local Security Checks	Local	high
345773	Amazon Linux 2 : rsyslog (ALAS-2026-3904)	Nessus	Amazon Linux Local Security Checks	Local	high
345768	Amazon Linux 2023 : rsyslog, rsyslog-crypto, rsyslog-elasticsearch (ALAS2023-2026-2133)	Nessus	Amazon Linux Local Security Checks	Local	high
341131	Linux Distros Unpatched Vulnerability : CVE-2026-78002	Nessus	Misc.	Local	high

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