CVE-2026-6478: PostgreSQL discloses MD5-hashed passwords via covert timing channel

Published May 14, 2026
·
Updated

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.

Other sources

PostgreSQL discloses MD5-hashed passwords via covert timing channel

— Microsoft

Affected Software

11 affected componentsFixes available
PostgreSQL postgresql<18.4, <17.10, <16.14, <15.18, <14.23
Microsoft azl3 postgresql 16.12-1
Patch available
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
debian/postgresql-13<=13.16-0+deb11u1, <=13.23-0+deb11u3
debian/postgresql-15<=15.17-0+deb12u1
15.18-0+deb12u1
debian/postgresql-17<=17.9-0+deb13u1
17.10-0+deb13u1
debian/postgresql-18
18.4-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade debian/postgresql-15 to a version that resolves this vulnerability.

    Fixed in 15.18-0+deb12u1
  2. Upgrade

    Upgrade debian/postgresql-17 to a version that resolves this vulnerability.

    Fixed in 17.10-0+deb13u1
  3. Upgrade

    Upgrade debian/postgresql-18 to a version that resolves this vulnerability.

    Fixed in 18.4-1
  4. Upgrade

    Upgrade PostgreSQL to a version that resolves this vulnerability.

    Fixed in 14.23
  5. Upgrade

    Upgrade PostgreSQL to a version that resolves this vulnerability.

    Fixed in 15.18
  6. Upgrade

    Upgrade PostgreSQL to a version that resolves this vulnerability.

    Fixed in 16.14
  7. Upgrade

    Upgrade PostgreSQL to a version that resolves this vulnerability.

    Fixed in 17.10
  8. Upgrade

    Upgrade PostgreSQL to a version that resolves this vulnerability.

    Fixed in 18.4

Event History

May 14, 2026
CVE Published
via MITRE·01:00 PM
Data Sourced
via MITRE·01:00 PM
DescriptionSeverityWeakness
Data Sourced
via Red Hat·02:02 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
RemedyDescriptionSeverityWeaknessAffected Software
May 16, 2026
Data Sourced
via Microsoft·08:03 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:03 AM
DescriptionSeverity
May 21, 2026
Data Sourced
via Launchpad·10:49 PM
Description
May 22, 2026
Data Sourced
via Ubuntu·10:49 PM
RemedyDescriptionSeverityAffected Software
May 25, 2026
Data Sourced
via Debian·10:55 PM
DescriptionAffected Software
Aug 5, 2026
Data Sourced
via IBM·12:00 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is the severity of CVE-2026-6478?

CVE-2026-6478 is classified as a high severity vulnerability due to the potential exposure of user credentials.

2

How do I fix CVE-2026-6478?

To fix CVE-2026-6478, update PostgreSQL to a version that is not affected, specifically switching to scram-sha-256 authentication.

3

Which versions of PostgreSQL are affected by CVE-2026-6478?

CVE-2026-6478 affects PostgreSQL versions up to 18.4, 17.10, 16.14, 15.18, and 14.23.

4

What impact does CVE-2026-6478 have on PostgreSQL security?

CVE-2026-6478 allows attackers to potentially recover user credentials, compromising the authentication process.

5

Is the scram-sha-256 password method affected by CVE-2026-6478?

No, scram-sha-256 passwords are not affected by CVE-2026-6478 and should be used as a secure alternative.

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