The package github.com/gomarkdown/markdown is a Go library for parsing Markdown text and rendering as HTML. Processing a malformed input containing a < character that is not followed by a > character anywhere in the remaining text with a SmartypantsRenderer will lead to Out of Bounds read or a panic. This vulnerability is fixed with commit 759bbc3e32073c3bc4e25969c132fc520eda2778.
Weakness
The product reads data past the end, or before the beginning, of the intended buffer.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Markdown | Gomarkdown | * | 2026-04-10 (excluding) |
| Multicluster Global Hub 1.4.5 | RedHat | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779579439 | * |
| Multicluster Global Hub 1.5.4 | RedHat | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1778867753 | * |
| Multicluster Global Hub 1.6.2 | RedHat | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1780167118 | * |
| Multicluster Global Hub 1.7.1 | RedHat | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779925273 | * |
| Red Hat Advanced Cluster Management for Kubernetes 2.15 | RedHat | rhacm2/acm-grafana-rhel9:1780677003 | * |
Potential Mitigations
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.