Dgraph: Pre-Auth Full Database Exfiltration via DQL Injection in NQuad Lang Field

## 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 requires two HTTP POSTs to port 8080. The first sets up a schema predicate with `@unique @index(exact) @lang` via `/alter` (also unauthenticated in default config). The second sends a crafted JSON mutation to `/mutate?commitNow=true` where a JSON key contains the predicate name followed by `@` and a DQL injection payload in the language tag position. The injection exploits the `addQueryIfUnique` function in `edgraph/server.go`, which constructs DQL queries using `fmt.Sprintf` with unsanitized `predicateName` that includes the raw `pred.Lang` value. The `Lang` field is extracted from JSON mutation keys by `x.PredicateLang()`, which splits on `@`, and is never validated by any function in the codebase. The attacker injects a closing parenthesis to escape the `eq()` function, adds an arbitrary named query block, and uses a `#` comment to neutralize trailing template syntax. The injected query executes server-side and its results are returned in the HTTP response. POC clip: https://github.com/user-attachments/assets/bbfb7bba-c957-4b57-b534-48a958314186 ## 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 | Two requests, deterministic outcome, no special conditions | | 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 mutation that carries the injection also writes data; the attacker can also set up arbitrary schema via unauthenticated /alter | | Availability | None | No denial of service | ## 3. Vulnerability Summary | Field | Value | | ----- | --------------------------------------------------------------------------- | | Title | Pre-Auth DQL Injection via Unsanitized NQuad Lang Field in addQueryIfUnique | | Type | Injection | | CWE | CWE-943 (Improper Neutralization of Special Elements in Data Query Logic) | | CVSS | 9.8 | ## 4. Target Information | Field | Value | | --------------------- | ------------------------------------------------------------------------------------------------------------------------ | | Pr

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Severity from

GitHub (reviewed advisory)

Weakness

CWE-943

Also known as

CVE-2026-41328, GO-2026-5749

• github.com/dgraph-io/dgraph/security/advisories/GHSA-x92x-px7w-4gx4
• nvd.nist.gov/vuln/detail/CVE-2026-41328
• github.com/dgraph-io/dgraph