Hamba avro is a go lang encoder/decoder implementation of the avro codec specification. In affected versions a well-crafted string passed to avro's `github.com/hamba/avro/v2.Unmarshal()` can throw a `fatal error: runtime: out of memory` which is unrecoverable and can cause denial of service of the consumer of avro. The root cause of the issue is that avro uses part of the input to `Unmarshal()` to determine the size when creating a new slice and hence an attacker may consume arbitrary amounts of memory which in turn may cause the application to crash. This issue has been addressed in commit `b4a402f4` which has been included in release version `2.13.0`. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Affected: Go: github.com/hamba/avro, Go: github.com/hamba/avro/v2
### Summary A well-crafted string passed to avro's `github.com/hamba/avro/v2.Unmarshal()` can throw a `fatal error: runtime: out of memory` which is unrecoverable and can cause denial of service of the consumer of avro.
### Details The root cause of the issue is that avro uses part of the input to `Unmarshal()` to determine the size when creating a new slice.
In the reproducer below, the first few bytes determine the size of the slice.
The root cause is on line 239 here: https://github.com/hamba/avro/blob/3abfe1e6382c5dccf2e1a00260c51a64bc1f1ca1/reader.go#L216-L242
### PoC The issue was found during a security audit of Dapr, and I attach a reproducer that shows how the issue affects Dapr.
Dapr uses an older version of the avro library, but it is also affected if bumping avro to latest.
To reproduce: ```bash cd /tmp git clone --depth=1 https://github.com/dapr/components-contrib cd components-contrib/pubsub/pulsar ``` now add this test to the `pulsar_test.go`: ```golang func TestParsePublishMetadata2(t *testing.T) { m := &pubsub.PublishRequest{} m.Data = []byte{246, 255, 255, 255, 255, 10, 255, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32} _, _ = parsePublishMetadata(m, schemaMetadata{protocol: avroProtocol, value: "bytes"}) } ``` run the test with `go test -run=TestParsePublishMetadata2`.
You should see this stack…