CVE-2026-6477

Description

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.

CVSS v3.1 Score

8.8

HIGH

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

EPSS — Exploit Prediction

0.0005

Probability of exploitation

0.15%

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-242 CWE-242

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-2026-6477/

Frequently Asked Questions

What is CVE-2026-6477? +

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

How severe is CVE-2026-6477? +

CVE-2026-6477 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 0.0005, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-6477? +

CVE-2026-6477 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-2026-6477? +

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.

Related Vulnerabilities

CVE-2024-52324 9.8

Ruijie Reyee OS versions 2.206.x up to but not including 2.320.x uses an inherently dangerous function which could allow an …

CVE-2025-49215 8.8

A post-auth SQL injection vulnerability in the Trend Micro Endpoint Encryption PolicyServer could allow an attacker to escalate privileges on …

CVE-2025-1331 7.8

IBM CICS TX Standard 11.1 and IBM CICS TX Advanced 10.1 and 11.1 could allow a local user to execute …

CVE-2025-1994 7.8

IBM Cognos Command Center 10.2.4.1 and 10.2.5 could allow a local user to execute arbitrary code on the system due …

CVE-2024-1597 10.0

pgjdbc, the PostgreSQL JDBC Driver, allows attacker to inject SQL if using PreferQueryMode=SIMPLE. Note this is not the default. In …

CVE-2026-6637 8.8

Stack buffer overflow in PostgreSQL module "refint" allows an unprivileged database user to execute arbitrary code as the operating system …