CVE-2024-56527VulnerabilityPublished 27 Dec 2024Updated 3 Nov 2025

CVE-2024-56527: tecnick tcpdf · XSS or 'Cross-site Scripting'

Affects tecnick tcpdfSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 6.8.0 soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 55% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.8.0

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

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 2026-10-26.

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 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

Upgrade tecnick/tcpdf to 6.8.0.

Affected software

Product	Affected	Fixed in
Packagisttecnick/tcpdf`pkg:composer/tecnick/tcpdf`Other threats	Affected <6.8.0	Fixed in 6.8.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Upgrade TCPDF to version 6.8.0 or later as soon as it becomes available to ensure the Error function properly sanitizes error messages. 2. In the interim, implement manual input validation and output encoding on all error messages generated by TCPDF to neutralize potentially malicious content. 3. Employ web application firewalls (WAFs) with rules targeting common XSS payloads to detect and block exploitation attempts. 4. Conduct thorough code reviews and security testing on applications integrating TCPDF to identify and remediate any unsafe error handling or input processing. 5. Monitor logs for unusual error message patterns or spikes in PDF generation failures that could indicate exploitation attempts. 6. Educate development teams on secure coding practices related to input sanitization and error handling to prevent similar vulnerabilities. 7. Isolate PDF generation services where possible to limit the blast radius of potential attacks. 8. Maintain an incident response plan tailored to web application vulnerabilities to enable rapid containment and recovery if exploitation occurs.

Description

An issue was discovered in TCPDF before 6.8.0. The Error function lacks an htmlspecialchars call for the error message.

Impact

For European organizations, the vulnerability poses a risk primarily to the availability of services that rely on TCPDF for PDF generation, such as invoicing systems, reporting tools, and document management platforms. Disruption of PDF generation can lead to operational delays, loss of business continuity, and reputational damage, especially in sectors like finance, healthcare, and government where document integrity and availability are critical. Although the vulnerability does not directly compromise confidentiality or integrity, successful exploitation could be leveraged as part of a broader attack chain, potentially facilitating phishing or session hijacking if combined with other vulnerabilities. The lack of authentication and user interaction requirements lowers the barrier for attackers, increasing the likelihood of exploitation in exposed environments. European organizations with extensive PHP-based web infrastructure and digital document workflows are particularly vulnerable. The absence of known exploits provides a window for proactive mitigation, but the high severity score underscores the urgency of addressing the issue to prevent future incidents.

Summary

CVE-2024-56527 identifies a cross-site scripting (XSS) vulnerability in the TCPDF library, a widely used PHP class for generating PDF documents. The vulnerability stems from the Error function's failure to sanitize error messages via htmlspecialchars, which is critical to neutralize potentially malicious HTML or JavaScript content. Without this sanitization, an attacker can inject crafted input that is reflected in error messages and rendered in the context of a web page or PDF viewer interface, leading to XSS attacks. The vulnerability is exploitable remotely without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact primarily affects availability (A:H) by potentially causing denial of service through malformed error messages disrupting PDF generation or rendering. Confidentiality and integrity impacts are not directly indicated. The vulnerability affects all versions of TCPDF prior to 6.8.0, with no patches currently linked but an upgrade path implied. No known exploits have been reported in the wild yet, but the straightforward nature of the flaw and the high CVSS score (7.5) suggest a significant risk. The CWE-79 classification confirms the improper neutralization of input during web page generation, a common vector for XSS attacks. Organizations relying on TCPDF for dynamic PDF generation in web applications should be aware of this flaw and take immediate action to remediate or mitigate the risk.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

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

WeaknessesCWE-79

Technical details

References

Community reviews

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