vulnerability / NVI-00015144 / Revision 2
Mermaid configuration APIs allow prototype pollution
GitHub lists this reviewed advisory for mermaid, mermaid. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
0.353%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.29059. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
mermaid
source listed>= 11.0.0-alpha.1, < 11.16.1
### Summary Mermaid's configuration setters (`mermaid.initialize`, `mermaidAPI.setConfig`, and `mermaidAPI.updateSiteConfig`) merge the caller-supplied configuration object into Mermaid's internal config using the `assignWithDepth` deep-merge helper that is vulnerable to prototype pollution. Because these APIs are intended to receive **trusted** configuration supplied by the application integrating Mermaid, Mermaid assesses the practical risk as **low**. The vulnerability is only reachable if an application forwards attacker-controlled data directly into one of these configuration entry points, which is outside their documented usage. User-controlled configuration (e.g. configuration in diagram code using `%%{init: {}}%%` or YAML frontmatter) are already protected from prototype pollution. ### Patches This has been patched in https://github.com/mermaid-js/mermaid/commit/2cd6dcf735533b323507e3e889ffdea870540b43 and released in Mermaid v11.16.1. A backport has been made for the v10 branch in c34b07a0815842327e70794d69b0c8c5a1e2a956 and was released in [Mermaid v10.9.8](https://github.com/mermaid-js/mermaid/
mermaid
source listed< 10.9.8
### Summary Mermaid's configuration setters (`mermaid.initialize`, `mermaidAPI.setConfig`, and `mermaidAPI.updateSiteConfig`) merge the caller-supplied configuration object into Mermaid's internal config using the `assignWithDepth` deep-merge helper that is vulnerable to prototype pollution. Because these APIs are intended to receive **trusted** configuration supplied by the application integrating Mermaid, Mermaid assesses the practical risk as **low**. The vulnerability is only reachable if an application forwards attacker-controlled data directly into one of these configuration entry points, which is outside their documented usage. User-controlled configuration (e.g. configuration in diagram code using `%%{init: {}}%%` or YAML frontmatter) are already protected from prototype pollution. ### Patches This has been patched in https://github.com/mermaid-js/mermaid/commit/2cd6dcf735533b323507e3e889ffdea870540b43 and released in Mermaid v11.16.1. A backport has been made for the v10 branch in c34b07a0815842327e70794d69b0c8c5a1e2a956 and was released in [Mermaid v10.9.8](https://github.com/mermaid-js/mermaid/
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-c4c3-pg64-4m4v ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-71438 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.