GHSA-mrxx-39g5-ph77 Dgraph: Pre-Auth Full Database Exfiltration via DQL Injection in Upsert Condition Field

• Go github.com/dgraph-io/dgraph/v25: < 25.3.3 → fixed in 25.3.3 • Go github.com/dgraph-io/dgraph/v24: <= 24.1.8 (no fix yet) • Go github.com/dgraph-io/dgraph: <= 1.2.8 (no fix yet)

1. Executive Summary A vulnerability has been found in Dgraph that gives an unauthenticated attacker full read access to every piece of data in the database. This affects Dgraph's default configuration where ACL is not enabled. The attack is a single HTTP POST to `/mutate?commitNow=true` containing a crafted `cond` field in an upsert mutation. The `cond` value is concatenated directly into a DQL query string via `strings.Builder.WriteString` after only a cosmetic `strings.Replace` transformation. No escaping, parameterization, or structural validation is applied. An attacker injects an additional DQL query block into the `cond` string, which the DQL parser accepts as a syntactically valid named query block. The injected query executes server-side and its results are returned in the HTTP response. There are no credentials involved. When ACL is disabled (the default), the `/mutate` endpoint requires no authentication. The `authorizeQuery` and `authorizeMutation` functions both return `nil` immediately when `AclSecretKey` is not configured. Even when ACL is enabled, a user with mutation-only permission can inject read queries that bypass per-predicate ACL authorization, because the injected query block is not subject to the normal authorization flow. POC clip: https://github.com/user-attachments/assets/edf43615-b0d5-46cd-abd9-2cb9423790d2 2. CVSS Score CVSS 3.1: 9.1 (Critical) ``` CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N ``` | Metric | Value | Rationale | | ------------------- | --------- | ---------------------------------------------------------------------------------- | | Attack Vector | Network | HTTP POST to port 8080 | | Attack Complexity | Low | Single request, no special conditions beyond default config | | Privileges Required | None | No authentication when ACL is disabled (default) | | User Interaction | None | Fully automated | | Scope | Unchanged | Stays within the Dgraph data layer | | Confidentiality | High | Full database exfiltration: all nodes, all predicates, all values | | Integrity | High | The injection can also be used to manipulate upsert conditions, bypassing uniqueness constraints and conditional mutation logic | | Availability | None | No denial of service | 3. Vulnerability Summary | Field | Value | | --------- | ------------------------------------------------------------------------------------------ | | Title | Pre-Auth DQL Injection via Unsanitized Cond Field in Upsert Mutations | | Type | Injection | | CWE | CWE-943 (Improper Neutralization of Special Elements in Data Query Logic) | | CVSS | 9.8 | 4. Target Information | Field | Value | | -------------------- | ---------------------------------------------------------------------------------------------- | | Project | Dgraph | | Repository | https://github.com/dgraph-io/dgraph | | Tested version | v25.3.0 | | HTTP handler | `dgraph/cmd/alpha/http.go` line 345 (`mutationHandler`) | | Cond extraction | `dgraph/cmd/alpha/http.go` line 413 (`strconv.Unquote`) | | Cond passthrough | `edgraph/server.go` line 2011 (`ParseMutationObject`, copies `mu.Cond` verbatim) | | Injection sink | `edgraph/server.go` line 750 (`upsertQB.WriteString(cond)`) | | Only transformation | `edgraph/server.go` line 730 (`strings.Replace(gmu.Cond, "@if", "@filter", 1)`) | | Auth bypass (query) | `edgraph/access.go` line 958 (`authorizeQuery` returns nil when `AclSecretKey == nil`) | | Auth bypass (mutate) | `edgraph/access.go` line 788 (`authorizeMutation` returns nil when `AclSecretKey == nil`) | | Response exfiltration| `dgraph/cmd/alpha/http.go` line 498 (`mp["queries"] = json.RawMessage(resp.Json)`) | | HTTP port | 8080 (default) | | Prerequisite | None. Default configuration. ACL disabled is the default. | 5. Test Environment | Component | Version / Details | | -------------------- | --------------------------------------------------------------- | | Host OS | macOS (darwin 25.3.0) | | Dgraph | v25.3.0 via `dgraph/dgraph:latest` Docker image | | Docker Compose | 1 Zero + 1 Alpha, default config, `--security whitelist=0.0.0.0/0` | | Python | 3.x with `requests` | | Network | localhost (127.0.0.1) | 6. Vulnerability Detail Location: `edgraph/server.go` lines 714-757 (`buildUpsertQuery`) CWE: CWE-943 (Improper Neutralization of Special Elements in Data Query Logic) The `/mutate` endpoint accepts JSON bodies containing a `mutations` array. Each mutation can include a `cond` field, intended for conditional upserts with syntax like `@if(eq(name, "Alice"))`. This condition is supposed to be spliced into the DQL query as a `@filter` clause on a dummy `var(func: uid(0))` block. The handler at `http.go:413` extracts the `cond` value via `strconv.Unquote`, which interprets `\n` as actual newlines but performs no sanitization: ```go mu.Cond, err = strconv.Unquote(string(condText.bs)) ``` `ParseMutationObject` at `server.go:2011` copies it verbatim: ```go res := &dql.Mutation{Cond: mu.Cond} ``` `buildUpsertQuery` at `server.go:730` applies one cosmetic replacement then concatenates the raw string directly into the DQL query: ```go cond := strings.Replace(gmu.Cond, "@if", "@filter", 1) // ... x.Check2(upsertQB.WriteString(cond)) ``` There is no escaping, no parameterization, no structural validation, and no character allowlist between the HTTP input and the query string concatenation. An attacker crafts a `cond` value that closes the `@filter(...)` clause and opens an entirely new named query block: ``` @if(eq(name, "nonexistent")) leak(func: has(dgraph.type)) { uid name email secret } ``` After `buildUpsertQuery` processes this, the resulting DQL is: ```dql { q(func: uid(0x1)) { uid } __dgraph_upsertcheck_0__ as var(func: uid(0)) @filter(eq(name, "nonexistent")) leak(func: has(dgraph.type)) { uid name email secret } } ``` The DQL parser (`dql.ParseWithNeedVars`) accepts multiple query blocks within a single `{}` container. It parses `leak(...)` as a legitimate named query. The `validateResult` function at `parser.go:740` only checks for duplicate aliases and explicitly skips `var` queries. The injected query uses a unique alias, so validation passes. All three queries execute. The results of the injected `leak` block are serialized to JSON a…