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TCPDF has incorrect comparison

High severity GitHub Reviewed Published Dec 27, 2024 to the GitHub Advisory Database • Updated Nov 3, 2025

Package

composer tecnickcom/tcpdf (Composer)

Affected versions

< 6.8.0

Patched versions

6.8.0

Description

An issue was discovered in TCPDF before 6.8.0. unserializeTCPDFtag uses != (aka loose comparison) and does not use a constant-time function to compare TCPDF tag hashes.

References

Published by the National Vulnerability Database Dec 27, 2024
Published to the GitHub Advisory Database Dec 27, 2024
Reviewed Dec 27, 2024
Last updated Nov 3, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(48th percentile)

Weaknesses

Incorrect Comparison

The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses. Learn more on MITRE.

Access of Resource Using Incompatible Type ('Type Confusion')

The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type. Learn more on MITRE.

CVE ID

CVE-2024-56522

GHSA ID

GHSA-w95c-7994-ghpr

Source code

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