CVE-2026-6477

PostgreSQL libpq lo_* functions let server superuser overwrite client stack memory

HIGH

8.8

CVSS Score

Published: May 14, 2026 at 01:00 PM UTC

Updated: August 25, 2026 at 01:40 PM UTC

2 products affected across 2 vendorsPostgreSQLSelf-Service Automation Portal

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Severity

HIGH8.8

Exploit prediction

EPSS 0.5%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

PostgreSQL · PostgreSQL

95%

v < 14.2315 ≤ v < 15.1815.0 ≤ v < 15.1816 ≤ v < 16.1416.0 ≤ v < 16.1417 ≤ v < 17.1017.0 ≤ v < 17.1018 ≤ v < 18.418.0 ≤ v < 18.415 16 17 18

Affected range stops below 14.23, so it looks safe — our inference, not a vendor statement

Affected range stops below 15.18, so it looks safe — our inference, not a vendor statement

Affected range stops below 16.14, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.10, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4, so it looks safe — our inference, not a vendor statement

Self-Service Automation Portal · Red Hatrpm

60%

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://www.postgresql.org/support/security/CVE-2026-6477/