CVE-2026-6637

Published May 14, 2026

Last updated 7 days ago

CVSS high 8.8

Overview

Description
Stack buffer overflow in PostgreSQL module "refint" allows an unprivileged database user to execute arbitrary code as the operating system user running the database. A distinct attack is possible if the application declares a user-controlled column as a "refint" cascade primary key and facilitates user-controlled updates to that column. In that case, a SQL injection allows a primary key update value provider to execute arbitrary SQL as the database user performing the primary key update. Versions before PostgreSQL 18.4, 17.10, 16.14, 15.18, and 14.23 are affected.
Source
f86ef6dc-4d3a-42ad-8f28-e6d5547a5007
NVD status
Analyzed
Products
postgresql

Risk scores

CVSS 3.1

Type
Secondary
Base score
8.8
Impact score
5.9
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

f86ef6dc-4d3a-42ad-8f28-e6d5547a5007
CWE-89

Social media

Hype score
Not currently trending

  1. New PostgreSQL vulnerabilities were disclosed today, including issues related to code execution, SQL injection, and denial of service. Worth reviewing: • CVE-2026-6637 – potential code execution via refint • CVE-2026-6476 – SQL injection in pg_createsubscriber •

    @UpwindMDR

    14 May 2026

    350 Impressions

    0 Retweets

    2 Likes

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    1 Quote

  2. New PostgreSQL vulnerabilities were disclosed today, including issues related to code execution, SQL injection, and denial of service. Worth reviewing: • CVE-2026-6637 – potential code execution via refint • CVE-2026-6476 – SQL injection in pg_createsubscriber •

    @UpwindMDR

    14 May 2026

    6 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

Configurations

Related CVEs

  1. SQL injection in PostgreSQL pg_createsubscriber allows an attacker with pg_create_subscription rights to execute arbitrary SQL as a superuser. The attack takes effect when pg_createsubscriber next runs. Within major versions 17 and 18, minor versions before PostgreSQL 18.4 and 17.10 are affected. Versions before PostgreSQL 17 are unaffected.•CVE-2026-6476
  2. Use of inherently dangerous function PQfn(..., result_is_int=0, ...) in PostgreSQL libpq lo_export(), lo_read(), lo_lseek64(), and lo_tell64() functions allows the server superuser to overwrite a client stack buffer with an arbitrarily-large response. Like gets(), PQfn(..., result_is_int=0, ...) stores arbitrary-length, server-determined data into a buffer of unspecified size. Because both the \lo_export command in psql and pg_dump call lo_read(), the server superuser can overwrite pg_dump or psql stack memory. Versions before PostgreSQL 18.4, 17.10, 16.14, 15.18, and 14.23 are affected.•CVE-2026-6477
  3. Buffer over-read in PostgreSQL function pg_restore_attribute_stats() accepts array values of unmatched length, which causes query planning to read past end of one array. This allows a table maintainer to infer memory values past that array end. Within major version 18, minor versions before PostgreSQL 18.4 are affected. Versions before PostgreSQL 18 are unaffected.•CVE-2026-6575
  4. Symlink following in PostgreSQL pg_basebackup plain format and in pg_rewind allows an origin superuser to overwrite local files, e.g. /var/lib/postgres/.bashrc, that hijack the operating system account. It will remain the case that starting the server after these commands implicitly trusts the origin superuser, due to features like shared_preload_libraries. Hence, the attack has practical implications only if one takes relevant action between these commands and server start, like moving the files to a different VM or snapshotting the VM. Versions before PostgreSQL 18.4, 17.10, 16.14, 15.18, and 14.23 are affected.•CVE-2026-6475
  5. Covert timing channel in comparison of MD5-hashed password in PostgreSQL authentication allows an attacker to recover user credentials sufficient to authenticate. This does not affect scram-sha-256 passwords, the default in all supported releases. However, current databases may have MD5-hashed passwords originating in upgrades from PostgreSQL 13 or earlier. Versions before PostgreSQL 18.4, 17.10, 16.14, 15.18, and 14.23 are affected.•CVE-2026-6478

References

Sources include official advisories and independent security research.