CVE-2026-6637

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.

CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.13%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-89 SQL Injection

CWE-121 CWE-121

Affected Products

Vendor	Product	Versions
postgresql	postgresql	< 14.23
postgresql	postgresql	15.0 — 15.18
postgresql	postgresql	16.0 — 16.14
postgresql	postgresql	17.0 — 17.10
postgresql	postgresql	18.0 — 18.4

References

Advisories & Patches

https://www.postgresql.org/support/security/CVE-2026-6637/

Frequently Asked Questions

What is CVE-2026-6637? +

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. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-6637? +

CVE-2026-6637 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-6637? +

CVE-2026-6637 affects products from postgresql, specifically: postgresql. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-6637? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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