CVE-2026-6637 | PostgreSQL refint allows stack buffer overflow and SQL injection

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.

Published: 2026-05-14 Last update: 2026-05-18 Assigner: f86ef6dc-4d3a-42ad-8f28-e6d5547a5007 Source: f86ef6dc-4d3a-42ad-8f28-e6d5547a5007
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-6637 is rated Low Risk (39.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.04%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-6637

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-15 — 0.04% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-6637

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 f86ef6dc-4d3a-42ad-8f28-e6d5547a5007

Weakness enumeration for CVE-2026-6637

GitHub Security Advisory for CVE-2026-6637

GHSA-96xx-m79q-xh44 · Severity: high — Stack buffer overflow in PostgreSQL module "refint" allows an unprivileged database user to...

OS Trackers for CVE-2026-6637

vendor priority summary link
debian not yet assigned CVE-2026-6637 not yet assigned priority: Debian including 4 source packages (postgresql-13, postgresql-15, postgresql-17, postgresql-18), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2026-6637
suse high CVE-2026-6637 severity important: SUSE including 176 source package names (libecpg6-17.10-3.27.1, libecpg6-18.4-150200.5.12.1, …), 773 product×package rows across 31 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS, SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, … (31 product lines)): First Fixed 340, Fixed 269, Known Not Affected 164. https://www.suse.com/security/cve/CVE-2026-6637/
ubuntu medium CVE-2026-6637 medium priority: Ubuntu including 8 source packages (postgresql-10, postgresql-12, …), 44 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 28, needs-triage 7, ignored 4, released 4, deferred 1. https://ubuntu.com/security/CVE-2026-6637

Affected software / configurations for CVE-2026-6637

Vendor Product Version Raw CPE
postgresql postgresql < 14.23 cpe:2.3:a:postgresql:postgresql:*:*:*:*:*:*:*:*
postgresql postgresql >= 15.0, < 15.18 cpe:2.3:a:postgresql:postgresql:*:*:*:*:*:*:*:*
postgresql postgresql >= 16.0, < 16.14 cpe:2.3:a:postgresql:postgresql:*:*:*:*:*:*:*:*
postgresql postgresql >= 17.0, < 17.10 cpe:2.3:a:postgresql:postgresql:*:*:*:*:*:*:*:*
postgresql postgresql >= 18.0, < 18.4 cpe:2.3:a:postgresql:postgresql:*:*:*:*:*:*:*:*

References for CVE-2026-6637

cvelogic Threat Intelligence