External risk intelligence

DBD::Pg Heap Out-of-Bounds Write Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-78183

This is a library-level vulnerability in a Perl database interface. While reachable via application code processing user-supplied inputs, the vulnerability is not exposed directly on the network edge by default. Reachability depends entirely on how a specific application uses the affected library to handle untrusted input, making it possible but not inherently internet-facing.

Out-of-bounds Write

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory concerns a critical vulnerability in a Perl module used for PostgreSQL database interactions. The issue involves a memory writing error within a function that handles numeric data, potentially allowing for unauthorized access and modification of data if triggered through specific application code. The main concern is confirming relevance and exposure within your environment.

A memory error can occur with numeric data handling.
Leadership should remember its potential to impact data integrity.
Confirm if this database library is in use to assess risk.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted input to an application that uses the affected Perl module. This input would be processed by the `quote_float` function, which incorrectly handles certain numeric literals. This error could allow an attacker to write data out of bounds in memory.

Entry Condition: Application uses the affected Perl module.
Trigger Point: Sending specific numeric literals to `$dbh->quote()`.
Resulting Risk: Memory corruption and potential code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could impact applications using DBD::Pg for Perl when processing specific numeric literals. An attacker could potentially trigger a heap out-of-bounds write by manipulating input passed to the `$dbh->quote` method with special values like "Infinity." This could lead to a crash or corruption of the application's memory.

Application memory and stability.
Specially crafted numeric literals.
Potential application crash or memory corruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the DBD::Pg Perl module's `quote_float` function presents a critical risk. Application owners and platform teams are likely responsible for identifying and remediating this issue, as it affects how database literals are handled. The first practical step involves locating all instances of DBD::Pg, assessing their exposure to untrusted input, and prioritizing remediation based on business criticality.

Application and platform teams own remediation.
Verify library usage and data input paths.
Plan updates during the next maintenance window.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is DBD::Pg and how is it used?

DBD::Pg is a Perl module that acts as a database interface, specifically allowing Perl applications to communicate with PostgreSQL databases. Developers use this library to execute SQL queries, manage database connections, and safely format data values for database storage within their custom software projects.

What does heap out-of-bounds write mean in CVE-2026-78183?

This refers to a memory management weakness, classified as CWE-787. In this case, the software calculates the required memory space incorrectly when processing certain numeric values. This causes the program to write data past the intended memory buffer, which can corrupt application memory and potentially disrupt stability or lead to unintended code execution.

How is this vulnerability triggered?

An attacker triggers this by providing specific numeric literals, such as 'Infinity', to the $dbh->quote method within an application using the affected library. The bug does not trigger during standard numeric operations; it requires the application to process these specific keyword-based values through the vulnerable quote_float function.

Is this vulnerability internet-facing?

According to Halo Surface Signal, this is not inherently internet-facing. As a library-level component, the risk depends on whether your specific application code takes untrusted user input and passes it into the vulnerable database quoting function. Its exposure is determined by your application's design rather than the library's default configuration.

What should I do if I use DBD::Pg?

First, conduct an inventory to locate all applications in your environment that rely on the DBD::Pg library. Once identified, evaluate if these applications pass external or untrusted data into the database quoting methods. Coordinate with your development or platform teams to prioritize and apply the necessary library updates during your next scheduled maintenance.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.