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.
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
| Link | Tags |
|---|---|
| https://github.com/rsyslog/rsyslog/security/advisories/GHSA-ggw7-xr6h-mmr8 | third party advisory |
| https://github.com/rsyslog/rsyslog/commit/f211042ecbb472f9d8beb4678a65d272b6f07705 | third party advisory patch |
| https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GMNNXLCU2UORRVSZO24HL4KMVPK5PHVW/ | vendor advisory |
| https://lists.debian.org/debian-lts-announce/2022/05/msg00028.html | third party advisory mailing list |
| https://www.debian.org/security/2022/dsa-5150 | third party advisory vendor advisory |
| https://security.netapp.com/advisory/ntap-20221111-0002/ | third party advisory |