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The `postgres-protocol` crate, a popular Rust library for implementing PostgreSQL wire protocol clients, contains a vulnerability in its handling of the PostgreSQL `hstore` data type. The `hstore` type is a key-value store often used to store semi-structured data within a PostgreSQL database. When a PostgreSQL server returns a binary-encoded `hstore` value to a client using this library, the client’s decoding routine—specifically the `postgres_protocol::types::hstore_from_sql` function—parses the binary data according to a specific format.
The vulnerability arises because the library does not properly validate the internal length field of the binary `hstore` representation before using it in memory operations. A malicious or compromised PostgreSQL server can craft a response containing a binary `hstore` value with an invalid internal length field. When the client library attempts to decode this malformed value, the invalid length triggers a panic in the Rust runtime, causing the client application to crash abruptly.
This panic constitutes a denial-of-service (DoS) condition. The crash is immediate and does not require any user interaction or elevated privileges on the client side. The attack vector is network-based, as the malicious response must be sent over the PostgreSQL wire protocol connection. The vulnerability affects all versions of the `postgres-protocol` crate prior to 0.6.12.
It is important to note that this issue only manifests when a client connects to an untrusted or potentially compromised PostgreSQL server. Applications that exclusively connect to trusted, internally managed databases are not at risk. However, the threat model is significant for clients that allow connections to user-supplied database servers, or for scenarios where a man-in-the-middle (MITM) attacker can intercept and modify the network traffic between the client and the server. In such cases, an attacker could inject a malicious `hstore` response to repeatedly crash client applications, disrupting service availability.
DailyCVE Form:
Platform: postgres-protocol (crates.io)
Version: < 0.6.12
Vulnerability: Panic on malformed hstore
Severity: Medium (CVSS 6.9)
Date: June 12, 2026
Prediction: Patch already available (0.6.12)
What Undercode Say:
Analytics
The vulnerability resides in the `postgres_protocol::types::hstore_from_sql` function, which is responsible for deserializing binary `hstore` data from the PostgreSQL wire protocol. The core issue is a lack of input validation on the length field embedded in the binary format. This allows an attacker to specify a length that, when used in subsequent memory operations (such as slicing or allocation), causes the Rust runtime to panic.
The attack is exploitable over the network with low complexity and requires no privileges. The CVSS v4.0 vector is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N, resulting in a base score of 6.9 (Medium). The impact is limited to the availability of the vulnerable system, with no effect on confidentiality or integrity.
Exploit (Educational Purposes!)
To trigger the vulnerability, an attacker controlling the PostgreSQL server (or able to intercept the connection) would send a `DataRow` message containing a binary `hstore` value. The malformed payload would include an internal length field that is inconsistent with the actual data size, for example:
Conceptual representation of a malformed hstore binary payload The length field (first 4 bytes) is set to an invalid value, e.g., 0xFFFFFFFF echo -ne "\xFF\xFF\xFF\xFF" | nc -l -p 5432
Alternatively, using a compromised or malicious PostgreSQL server, an attacker could modify the server’s response logic to return such a payload for a specific query:
-- On a malicious PostgreSQL server, a trigger or function could be crafted -- to return a malformed hstore value when a client executes a SELECT query. CREATE OR REPLACE FUNCTION malicious_hstore() RETURNS hstore AS $$ BEGIN -- Return a binary hstore with an invalid length field -- This is a conceptual representation; actual exploitation requires -- crafting the binary protocol message directly. RETURN 'malformed'::hstore; END; $$ LANGUAGE plpgsql;
When the client application issues a query that causes the server to return this malformed hstore, the `postgres_protocol` crate will panic, crashing the client.
Protection
The vulnerability is fixed in version `0.6.12` of the `postgres-protocol` crate. All users are strongly advised to update to this version or later. The fix involves adding proper validation of the internal length field before it is used in memory operations, ensuring that malformed data does not cause a panic.
To update the dependency, modify your `Cargo.toml` file:
[bash] postgres-protocol = "0.6.12"
Alternatively, run:
cargo update -p postgres-protocol
If updating is not immediately possible, consider the following mitigations:
– Trusted Connections Only: Ensure that your application only connects to PostgreSQL servers that you trust and control.
– Network Security: Use network-level controls (e.g., firewalls, VPNs) to prevent man-in-the-middle attacks and unauthorized access to your database connections.
– Input Validation: While the vulnerability is on the client-side decoding, consider implementing application-level error handling to catch panics and gracefully restart or log errors, though this is a partial mitigation.
Impact
- Denial of Service: A successful attack causes the client application to panic and crash, leading to service unavailability.
- Wide Attack Surface: The vulnerability affects any Rust application using the `postgres-protocol` crate to connect to untrusted PostgreSQL servers.
- Low Complexity: The attack requires low complexity and no user interaction, making it easy to exploit.
- No Data Breach: The vulnerability does not allow data exfiltration or modification; its impact is limited to availability.
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Sources:
Reported By: github.com
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