CVE-2026-66838 SQL injection via the :comment option in Postgrex.stream/4
Attackers can inject SQL commands via the comment option in Postgrex.stream/4, allowing execution of arbitrary clauses under the database connection's role.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-66838?
CVE-2026-66838 is a medium-severity SQL injection vulnerability in elixir-ecto postgrex, published on 7 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') vulnerability in elixir-ecto postgrex allows SQL Injection via the :comment option of Postgrex.stream/4. An attacker who can influence that value can close the comment delimiter with */ and extend the streamed statement with their own clauses, which execute under the connection's role. Ecto exposes the same option through Ecto.Repo.stream/2.
Postgrex appends the comment by concatenating it into the statement text sent in the Parse message, without escaping or rejecting */. The option is validated by comment_not_present!/1 at every other execution point; stream/4 never calls it. Because Parse accepts a single command, the injection is confined to the streamed statement and further statements cannot be chained.
This issue affects postgrex: from 0.19.3 before 0.22.4.
Weakness: CWE-89
Which versions are affected by CVE-2026-66838?
1 open source package ship an affected version, including postgrex. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
postgrex Hex | From 0.19.3 | 0.22.4 |
Products include Elixir-Ecto Postgrex.
How do I fix CVE-2026-66838?
Upgrade postgrex to 0.22.4 or later.
Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.
Is CVE-2026-66838 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66838 exists.
Other vulnerabilities in elixir-ecto postgrex
Sources
Also known as EEF-CVE-2026-66838, GHSA-3gww-3f36-2388.