Rsyslog

Rsyslog is a rocket-fast system for log processing. From versions 1.15.0 to 8.2610.0, rsyslog's omfile dynaFile facility intentionally allows templates to generate flexible output paths. This supports valid deployments that route logs into different directories or use dynamically generated file names. A deployment becomes unsafe when a dynaFile template uses a value influenced by untrusted input as a path component without explicit secure-path handling. In that configuration, the rendered path can escape the operator's intended log directory. This is not limited to the RFC5424 HOSTNAME field. Any untrusted value that reaches a dynaFile path component can create the condition. At time of publication, there are no publicly available patches.

Published: 2026-10-22T13:32:56.695Z
Updated: 2026-10-29T02:15:30.165Z

Rsyslog is a rocket-fast system for log processing. From 8.2110.0 until 8.2604.0, the optional imhttp module's parse_auth_header function in contrib/imhttp/imhttp.c allocates a zero-byte heap buffer with calloc(0, len) when an HTTP Basic Authorization value exceeds its fixed work buffer, then passes that pointer to apr_base64_decode. An unauthenticated remote attacker can send an oversized encoded credential to an imhttp endpoint configured for Basic Authentication, causing decoded data to overwrite adjacent heap memory before credential validation. Deployments that do not install, load, and use imhttp with Basic Authentication are not affected. The demonstrated impact is a process crash that interrupts log collection, and code execution has not been demonstrated. This issue is fixed in version 8.2604.0.

Published: 2026-09-18T16:53:29.184Z
Updated: 2026-09-22T15:04:35.228Z

Rsyslog is a rocket-fast system for log processing. From 7.5.4 until 8.2606.0, the optional mmpstrucdata plugin's parseSD_PARAM function in plugins/mmpstrucdata/mmpstrucdata.c stores RFC5424 parameter values in a fixed pVal[32 * 1024] stack buffer and calls parsePARAM_VALUE without supplying the destination size. A remote unauthenticated attacker whose crafted RFC5424 message reaches an action using mmpstrucdata can provide a structured-data parameter larger than that buffer when MaxMessageSize permits it, causing an attacker-controlled stack overwrite. Deployments that do not install and use the plugin, or whose effective message-size limit remains below the required threshold, are not affected by this issue. The demonstrated impact is a crash and interruption of log collection; code execution is not demonstrated. This issue is fixed in version 8.2606.0.

Published: 2026-09-18T16:54:28.925Z
Updated: 2026-09-21T20:49:39.195Z

Rsyslog is a rocket-fast system for log processing. Modules for TCP syslog reception have a potential heap buffer overflow when octet-counted framing is used. This can result in a segfault or some other malfunction. As of our understanding, this vulnerability can not be used for remote code execution. But there may still be a slight chance for experts to do that. The bug occurs when the octet count is read. While there is a check for the maximum number of octets, digits are written to a heap buffer even when the octet count is over the maximum, This can be used to overrun the memory buffer. However, once the sequence of digits stop, no additional characters can be added to the buffer. In our opinion, this makes remote exploits impossible or at least highly complex. Octet-counted framing is one of two potential framing modes. It is relatively uncommon, but enabled by default on receivers. Modules `imtcp`, `imptcp`, `imgssapi`, and `imhttp` are used for regular syslog message reception. It is best practice not to directly expose them to the public. When this practice is followed, the risk is considerably lower. Module `imdiag` is a diagnostics module primarily intended for testbench runs. We do not expect it to be present on any production installation. Octet-counted framing is not very common. Usually, it needs to be specifically enabled at senders. If users do not need it, they can turn it off for the most important modules. This will mitigate the vulnerability.

Published: 2022-05-05T00:00:00.000Z
Updated: 2025-04-23T18:31:22.233Z

A denial of service vulnerability was found in rsyslog in the imptcp module. An attacker could send a specially crafted message to the imptcp socket, which would cause rsyslog to crash. Versions before 8.27.0 are vulnerable.

Published: 2019-01-25T18:00:00.000Z
Updated: 2024-08-05T10:32:54.189Z