VulnerabilityPublished 19 Apr 2024Updated 4 Nov 2025

CVE-2024-22640: ReDoS

Source CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 1.3% chance of exploitation in 30 days – higher than 70% 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: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 19 Apr 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 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

AI-suggested

1. Monitor TCPDF project repositories and security advisories for official patches addressing CVE-2024-22640 and apply updates promptly once available. 2. In the interim, implement strict input validation and sanitization to reject or neutralize suspicious or malformed color attributes in HTML content before processing. 3. Employ rate limiting and request throttling on endpoints that accept HTML input to reduce the risk of resource exhaustion from repeated exploit attempts. 4. Consider isolating PDF generation services in separate containers or sandboxed environments to limit the impact of potential denial of service. 5. Use Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the vulnerable regex patterns if signatures become available. 6. Audit and restrict access to PDF generation functionality to trusted users or internal systems where feasible. 7. Conduct performance monitoring and alerting on CPU usage spikes in services utilizing TCPDF to enable rapid detection of exploitation attempts. 8. Review and update incident response plans to include scenarios involving ReDoS attacks on document generation services.

Description

TCPDF version <=6.6.5 is vulnerable to ReDoS (Regular Expression Denial of Service) if parsing an untrusted HTML page with a crafted color.

Impact

For European organizations, the primary impact of this vulnerability is service availability disruption. Organizations that rely on TCPDF for dynamic PDF generation from user-supplied or external HTML content—such as government portals, financial institutions, healthcare providers, and e-commerce platforms—may experience denial of service conditions if targeted. This could lead to downtime, degraded user experience, and operational delays. While no data breach or integrity compromise is directly associated, prolonged or repeated outages could erode trust and cause financial losses. Additionally, automated systems that generate reports or documents on demand could be interrupted, affecting business continuity. The vulnerability's remote exploitability without authentication increases the attack surface, especially for public-facing services. Given the widespread use of PHP and TCPDF in Europe, the threat is relevant across multiple sectors. Organizations with stringent uptime requirements or those subject to regulatory compliance around service availability (e.g., financial and healthcare sectors) face heightened risk.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Regular Expression Exponential Blowup (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

Description

AI analysisMachine-generated, updated 11 Nov 2025, 01:31 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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