CVE-2026-116333
Description
A flaw was found in PostgreSQL. An authenticated database user with permission to create database objects can trigger a buffer over-read during parallel B-tree index scans by defining a function incorrectly marked as parallel safe or stable. This issue causes participating worker processes to generate inconsistent search keys, allowing the attacker to read arbitrary server memory and resulting in sensitive information disclosure.
Statement
This vulnerability is rated as Moderate severity because exploitation requires an authenticated database user with permissions to create custom functions, limiting unauthorized remote access. While an attacker can trigger out-of-bounds memory reads via manipulated parallel query scans, the flaw does not grant write access, data modification, or direct code execution. Earlier major database releases supported across standard enterprise platforms do not implement the vulnerable parallel scan mechanism and are not susceptible to this flaw.
Mitigation
To mitigate this issue without applying code fixes, parallel query execution can be disabled to prevent PostgreSQL from launching parallel workers for index scans:
1. Disable parallel worker processes by setting `max_parallel_workers_per_gather` to `0`. This can be applied across the instance by executing the following SQL command as an administrative user:
ALTER SYSTEM SET max_parallel_workers_per_gather = 0;
SELECT pg_reload_conf();
Alternatively, add or modify the setting in `/var/lib/pgsql/data/postgresql.conf`:
max_parallel_workers_per_gather = 0
Then reload the PostgreSQL service:
systemctl reload postgresql
2. As a supplementary operational control, restrict `CREATE` permissions on schemas and databases to trusted administrators to prevent untrusted users from declaring custom functions.
Caveats:
Disabling parallel query execution forces queries to run in a single process, which can degrade query performance on analytical workloads or large table scans.
Warning: Reloading PostgreSQL configuration files will apply changes to new queries and sessions without dropping active connections, but query execution characteristics will change immediately.
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 | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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