VulnerabilityPublished 27 Dec 2024Updated 3 Nov 2025

CVE-2024-56522: tecnick tcpdf · Type Confusion

Affects tecnick tcpdfSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Dec 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
tecnick tcpdf	Affected =0	Fixed in–

AI-suggested

Upgrade TCPDF to version 6.8.0 or later, where the vulnerability has been addressed with proper use of strict and constant-time comparisons.
Audit all applications using TCPDF to identify usage of unserializeTCPDFtag or similar unserialize functions and replace or harden them to avoid unsafe deserialization and timing leaks.
Implement application-layer input validation and sanitization to reduce the risk of malicious payloads triggering the vulnerability.
Employ web application firewalls (WAFs) with rules to detect and block suspicious requests targeting PDF generation endpoints.
Monitor application logs and network traffic for anomalous timing patterns or repeated requests that may indicate exploitation attempts.
Educate developers on secure coding practices related to serialization, deserialization, and cryptographic comparisons to prevent similar vulnerabilities.
Consider deploying runtime application self-protection (RASP) tools to detect and mitigate exploitation attempts in real time.

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.

Impact

For European organizations, the primary impact of CVE-2024-56522 is the potential disclosure of sensitive information through timing side-channel attacks against PDF generation processes using vulnerable TCPDF versions. This can compromise confidentiality of internal data, user information, or proprietary content embedded in PDFs. Sectors such as government, finance, healthcare, and legal services that frequently generate and distribute PDF documents programmatically are at higher risk. Exploitation could lead to leakage of personally identifiable information (PII), intellectual property, or confidential communications. Although the vulnerability does not directly affect system integrity or availability, the confidentiality breach can undermine trust, lead to regulatory non-compliance (e.g., GDPR), and cause reputational damage. The remote, unauthenticated nature of the exploit increases the attack surface, making it easier for threat actors to target European organizations with public-facing web applications using TCPDF.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2025, 20:04 UTC

WeaknessesCWE-843

Technical details

References

Community reviews

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