vulnerability / NVI-00015230 / Revision 1
cel-go: JSON Private Fields Exposed via NativeTypes and ParseStructTag
GitHub lists this reviewed advisory for github.com/google/cel-go. 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.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/google/cel-go
source listed>= 0.22.0, <= 0.28.1
The function `ext.NativeTypes(ParseStructTag("json"))` does not honour the `encoding/json` skip directive `json:"-"`. Fields tagged `json:"-"` are registered in the CEL type system under the literal name `"-"` and are readable from any user-submitted CEL expression via `dyn(obj)["-"]`. Additionally, `newNativeTypes` silently registers every nested struct reachable from the type passed to `NativeTypes`, including types from third-party dependencies the developer never examined. ## Root cause In `fieldNameByTag`, the helper used by `ParseStructTag("json")` to translate Go struct tags into CEL field names. See at `ext/native.go:146`: ```go func fieldNameByTag(structTagToParse string) func(field reflect.StructField) string { return func(field reflect.StructField) string { tag, found := field.Tag.Lookup(structTagToParse) if found { splits := strings.Split(tag, ",") if len(splits) > 0 { // We make the assumption that the leftmost entry in the tag is the name. // This seems to be true for most tags that have the concept of a name/key, such as: // https://pkg.go.dev/encoding/xml#Marshal
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.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-gcjh-h69q-9w9g ↗
GitHub Advisory Database · vendor advisory
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- Revision 1 ·
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