CVE-2024-56521Network attack vector

Content spoofing via disabled TLS certificate validation

Published Dec 27, 2024 · Updated Mar 24, 2025

Improper certificate validation in Tecnick.com LTD TCPDF before 6.8.0 allows man-in-the-middle attackers to substitute remote content. TCPDF_STATIC::url_exists and TCPDF_STATIC::fileGetContents set libcurl's peer and hostname verification options to false when fetching URLs. Exploitation requires the libcurl retrieval path and a position from which HTTPS traffic can be intercepted; successfully substituted data can alter content consumed during PDF generation.

CVSS severity8.2
High
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Tecnick.com LTD TCPDF before 6.8.0 allows man-in-the-middle attackers to substitute remote content. TCPDF_STATIC::url_exists and TCPDF_STATIC::fileGetContents set libcurl's peer and hostname verification options to false when fetching URLs. Exploitation requires the libcurl retrieval path and a position from which HTTPS traffic can be intercepted; successfully substituted data can alter content consumed during PDF generation.

The record

CVE
CVE-2024-56521
Published
Dec 27, 2024
Updated
Mar 24, 2025
Vendor
Tecnick.com LTD
Product
TCPDF
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 24, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <6.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Tecnick.com LTD · TCPDFversion=0 <6.8.0

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.2GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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