CVE-2026-19888
Description
A flaw was found in PgBouncer. Missing validation of a mandatory attribute in the SCRAM client-final-message parser allows an unauthenticated remote attacker to crash the process. By sending a malformed message, the parser can report success while a required value remains unset, leading to a NULL pointer dereference. This crash occurs before any credentials are verified and terminates all pooled connections, resulting in a Denial of Service.
Mitigation
To mitigate this issue, restrict network access to the PgBouncer service to only trusted clients or localhost. This can be achieved by configuring firewall rules to limit incoming connections to the PgBouncer port or by setting the `listen_addr` parameter in the `pgbouncer.ini` configuration file to `localhost` or specific trusted IP addresses. After modifying the `pgbouncer.ini` file, the PgBouncer service must be restarted for the changes to take effect, which will temporarily disrupt existing connections.
Example for `pgbouncer.ini`:
[pgbouncer]
listen_addr = 127.0.0.1
Example for firewall (adjust port if necessary, default is 6432):
bash
firewall-cmd --permanent --zone=public --remove-port=6432/tcp
firewall-cmd --permanent --zone=trusted --add-source=192.168.1.0/24 --add-port=6432/tcp
firewall-cmd --reload
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
