Answer in brief
CVE-2026-18248 records a Critical severity (CVSS 9.1) vulnerability in @fastify/aws-lambda vulnerable to Lambda event spoofing via client-controlled x-apigateway-event header. The current sources do not mark it as known exploited. The current feed maps @fastify/aws-lambda/@fastify/aws-lambda (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps @fastify/aws-lambda/@fastify/aws-lambda (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @fastify/aws-lambda/@fastify/aws-lambdageneric | >=6.4.0 <6.4.1 | 6.4.1 |
Published upstream
Aug 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 3, 2026
@fastify/aws-lambda version 6.4.0 decorates each Fastify request with request.awsLambda.event and request.awsLambda.context, values that applications are documented to use for authorization decisions such as reading API Gateway authorizer claims. In the default configuration, the getter that populates this decoration reads the client-controlled x-apigateway-event and x-apigateway-context HTTP headers before falling back to the trusted internal request token, and those reserved headers are not stripped from the incoming event. An unauthenticated attacker who can set a single HTTP header can therefore forge the entire Lambda proxy event, including the authorizer context, and override the genuine one. This results in a full authentication and authorization bypass and privilege escalation for any application that trusts request.awsLambda.event for identity or access control. Only version 6.4.0 is affected. Patches: upgrade to @fastify/aws-lambda 6.4.1, which resolves the decoration only through the internal per-invocation token and strips the reserved headers before the request is processed.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-18248 records a Critical severity (CVSS 9.1) vulnerability in @fastify/aws-lambda vulnerable to Lambda event spoofing via client-controlled x-apigateway-event header. The current sources do not mark it as known exploited. The current feed maps @fastify/aws-lambda/@fastify/aws-lambda (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps @fastify/aws-lambda/@fastify/aws-lambda (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @fastify/aws-lambda/@fastify/aws-lambdageneric | >=6.4.0 <6.4.1 | 6.4.1 |
Published upstream
Aug 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 3, 2026
@fastify/aws-lambda version 6.4.0 decorates each Fastify request with request.awsLambda.event and request.awsLambda.context, values that applications are documented to use for authorization decisions such as reading API Gateway authorizer claims. In the default configuration, the getter that populates this decoration reads the client-controlled x-apigateway-event and x-apigateway-context HTTP headers before falling back to the trusted internal request token, and those reserved headers are not stripped from the incoming event. An unauthenticated attacker who can set a single HTTP header can therefore forge the entire Lambda proxy event, including the authorizer context, and override the genuine one. This results in a full authentication and authorization bypass and privilege escalation for any application that trusts request.awsLambda.event for identity or access control. Only version 6.4.0 is affected. Patches: upgrade to @fastify/aws-lambda 6.4.1, which resolves the decoration only through the internal per-invocation token and strips the reserved headers before the request is processed.
Quoted source text, attributed separately from HOL analysis.