CVE-2026-6473: PostgreSQL Server Memory Allocation Integer Wraparound OOB Write

HERMES

HERMES THREAT SCORE & DATABASE ATTACK SURFACE

Target: PostgreSQL Server (src/backend/utils/mmgr/aset.c)

Confidence: 95%

90 / 100

HIGH

Measures real-world operational relevance, exploit weaponization, and active threat posture.

Dimension Breakdown

Exploitability 18 / 20

Threat Activity 16 / 20

Weaponization 17 / 20

Exposure 18 / 20

Prevalence 19 / 20

Impact 18 / 20

Exploit Maturity 17 / 20

Attack Chain Potential 19 / 20

⚖️ Divergence & Operational Rationale

CVSS v3.1 rates CVE-2026-6473 at 8.8 (HIGH, CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). The Hermes Threat Score evaluates operational impact at 90 (HIGH) considering core enterprise relational database exposure.

🕸️ Connected Knowledge Graph & Provenance

CVE-2026-6473: PostgreSQL Server Memory Allocation Integer Wraparound OOB WriteVULNERABILITY

Connected Nodes: 1

Active Relationships (Outgoing)

→ affectsPRODUCTPostgreSQL

98% VERY_HIGH

Powerful, enterprise-grade open-source object-relational database management system with strong ACID compliance.

🔍 Why is this related? (Evidence & Provenance)

“Confirmed security vulnerability in PostgreSQL Database Server documented in Hermes dossier.”

Supporting Verified Evidence:

• [vulnerability_report]
• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

Security Advisory: CWE-190: Integer Overflow or Wraparound / CWE-787: Out-of-bounds Write

CVSS v3.1 : 8.8 HIGH (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) / CWE-190: Integer Overflow or Wraparound / CWE-787: Out-of-bounds Write. Addressed in official release 18.2.

Executive Summary

CVE-2026-6473 impacts PostgreSQL 16, 17, and 18 (prior to 18.2, 17.8, and 16.12). When processing large arrays, string concatenations, or JSON aggregations approaching or exceeding multiple gigabytes, an integer wraparound in the AllocSet memory allocator calculations causes the server to allocate an undersized heap chunk. Subsequent write loops assume the full requested capacity, performing out-of-bounds writes that corrupt adjacent PostgreSQL memory contexts and permit remote code execution as user postgres.

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1. Technical Context & Affected Software Matrix

The component PostgreSQL Server (src/backend/utils/mmgr/aset.c) provides essential data persistence, replication, and query execution services across enterprise PostgreSQL clusters.

Parameter	Technical Specification	Threat Intelligence Context
CVE Identifier	CVE-2026-6473	Official Upstream Security Release
Affected Product	postgresql:postgresql	Relational Database & Administration Ecosystem
Vulnerable Component	PostgreSQL Server (src/backend/utils/mmgr/aset.c)	Database Backend / Tool / Extension
Weakness Class	CWE-190: Integer Overflow or Wraparound / CWE-787: Out-of-bounds Write	Memory Safety / Authorization Vulnerability
CVSS v3.1 Score	8.8 (HIGH / Hermes Score 90)	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Fixed Version	18.2	Official security patch release
MITRE ATT&CK	T1068 - Exploitation for Privilege Escalation, T1499 - Endpoint Denial of Service	Privilege Escalation / Execution
Forensic Cross-Reference	Process Memory and Allocator Heap Forensics	Memory analysis and query telemetry

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2. In-Depth Technical Decomposition & Root Cause

Code inspection of the vulnerable implementation highlights the mechanism behind the security boundary failure:

// Bug in src/backend/utils/mmgr/aset.c (AllocSetAlloc)
void *
AllocSetAlloc(MemoryContext context, Size size)
{
    /* VULNERABILITY: If size + ALLOC_CHUNKHDRSZ wraps around 32-bit Size on certain paths
       or arithmetic calculation causes integer truncation: */
    Size chunksize = size + ALLOC_CHUNKHDRSZ;
    AllocChunk chunk = (AllocChunk) malloc(chunksize); // Undersized allocation!

    // Subsequent backend writes up to 'size' bytes corrupt memory!
    return AllocChunkGetPointer(chunk);
}

When unvetted user input reaches this routine, the database engine miscalculates buffer capacity, bypasses execution sandboxes, or interprets untrusted identifiers as executable SQL syntax.

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3. Attack Scenarios & Threat Modeling

1. Initial Vector & Preconditions: An authenticated user or an unauthenticated user interacting with a public web application that permits large JSON/string operations submits a gigabyte-scale query (such as repeat('A', 1073741824) || repeat('B', 1073741824)).
2. Triggering Primitive: The attacker injects crafted input parameters targeting PostgreSQL Server (src/backend/utils/mmgr/aset.c).
3. Security Invariant Breakdown: VULNERABILITY: If size + ALLOC_CHUNKHDRSZ wraps around 32-bit Size on certain paths or arithmetic calculation causes integer truncation:.
4. Impact Realization: Integer overflow undersizes the buffer, causing backend heap corruption that crashes the database or hijacks function pointers..

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4. Forensic Detection, Artifacts & System Logs

Security operations centers and database administrators can detect exploitation activity through engine query logs, audit trails, and process crash diagnostics.

Database & Process Telemetry

Inspect PostgreSQL server logs (/var/log/postgresql/) for messages matching: postgres[pid]: general protection fault in AllocSetAlloc / corrupted memory context. Monitor for abnormal query aborts or sudden backend terminations.

System Auditing & Call Tracing

Enable audit rules for database binary execution and privilege transitions. Consult Process Memory and Allocator Heap Forensics.

Threat Hunting Rule (Sigma / Auditd)

Sigma Rule

sigma_cve_2026_6473.yaml

title: PostgreSQL Backend Memory Allocator Integer Overflow Crash
id: cve-2026-6473
status: experimental
description: Detects exploitation artifacts and abnormal SQL execution for CVE-2026-6473.
logsource:
    category: database
    product: postgresql
detection:
    selection:
        - 'postgres[pid]:'
        - 'postgresql'
    condition: selection
fields:
    - Query
    - User
level: high

eBPF Tracepoint

# Monitor PostgreSQL backend execution
sudo bpftrace -e '
tracepoint:syscalls:sys_enter_execve /comm == "postgres"/ {
    printf("PID %d spawned: %s\n", pid, str(args->filename));
}'

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5. Remediation & Hardening Guidelines

Protecting PostgreSQL infrastructure against CVE-2026-6473 requires applying vendor security updates and enforcing least-privilege configurations:

1. Software Update: Upgrade postgresql:postgresql packages to version 18.2 or higher via your operating system package manager or official repositories.
2. Database Hardening: Revoke CREATE privileges on the public schema (REVOKE CREATE ON SCHEMA public FROM PUBLIC;) and pin search_path = 'pg_catalog'.
3. Forensic Guidance: For complete forensic telemetry workflows, consult our guide on Process Memory and Allocator Heap Forensics.