# Impact
The Kiota PHP code generator is vulnerable to a code generation literal injection attack. The generator embeds string values from OpenAPI fields (e.g. `description`, default values, and property names) directly into PHP double-quoted string literals without properly escaping the `$` character. Since PHP evaluates string interpolation expressions like `"${expr}"`, `"$var"`, and `"{$obj->prop}"` within double-quoted strings at runtime, an attacker who controls an OpenAPI specification file can inject arbitrary PHP code into generated model and request-builder classes.
# Who is impacted
Developers using Kiota to generate PHP API clients from external or untrusted OpenAPI specifications
Teams with CI/CD pipelines configured to automatically regenerate client code from remote specs
Applications that deploy generated PHP code to production servers
# Vulnerability details
Affected component: `StringExtensions.cs`
Root cause: The shared `SanitizeDoubleQuote()` function in `Writers/StringExtensions.cs` does not escape the `$` character. As a result, any schema-derived string emitted as a PHP double-quoted literal preserves `$`-prefixed interpolation constructs (`${...}`, `$var`, `{$...}`) verbatim, which PHP evaluates at runtime instead of treating as literal text. This is the same class of code-generation literal-injection flaw previously fixed for the Ruby generator (`#` interpolation), recurring here as a missed variant for PHP's `$` interpolation in the sibling sanitizer helper.
# Attack vectors
OpenAPI `description` and default fields in schema properties
Property wire-name keys embedded in deserializer/serializer methods
Any schema-derived string embedded in PHP double-quoted literals
Severity: Critical when generated code reaches production; High for CI/CD environments with access to production secrets; Medium for public third-party specs; Low for developer-controlled specs.
# Patches
[#7863](https://github.com/microsoft/kiota/pull/7863)
# Workarounds
If you cannot upgrade immediately:
1. Audit and sanitize OpenAPI specifications: Review all OpenAPI specification files for any descriptions, default values, or property names containing the `$` character. Remove or replace any suspicious strings before code generation.
2. Code review of generated files: Implement mandatory code review of all generated PHP files before merging into any branch. Look for double-quoted strings containing `${`, `$var`, or `{$` patterns.
3. Restrict specification sources: Only consume OpenAPI specifications from trusted internal sources. Avoid automatic code generation from external or third-party APIs until this patch is applied.
4. Isolate generated code from production: Do not deploy generated PHP models to production environments unless the specification source has been verified and reviewed.
5. Manual escaping (temporary): If regeneration is not possible, manually inspect and edit generated files to escape any `$` characters in double-quoted string literals (replace `$` with `\$`).
# Remediation
Upgrade Kiota to 1.29.1, 1.32.4, or later.
Regenerate/refresh existing generated clients as a precaution:
Refreshing generated clients ensures previously generated vulnerable code is replaced with hardened output.
- Source published
- 24 Jul 2026 15:46:46 UTC
- Source modified
- 17 Aug 2026 15:00:08 UTC
- Observed here
- 23 Oct 2026 16:01:25 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Publisher rating · HIGH