# CVE-2024-56521: TCPDF missing certificate validation

> TCPDF disables SSL certificate verification when using libcurl, allowing attackers to bypass TLS security checks and potentially intercept or modify data.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Dec 2024
- **Updated:** 24 Mar 2025
- **Also known as:** DEBIAN-CVE-2024-56521, GHSA-9mgx-552f-59p6, UBUNTU-CVE-2024-56521

## What is CVE-2024-56521?

CVE-2024-56521 is a critical vulnerability in tecnick tcpdf, published on 27 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in TCPDF before 6.8.0. If libcurl is used, CURLOPT_SSL_VERIFYHOST and CURLOPT_SSL_VERIFYPEER are set unsafely.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2024-56521?

2 open source packages ship an affected version, including tecnickcom/tcpdf. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `tecnickcom/tcpdf` | Packagist | All versions | 6.8.0 |
| `tecnickcom/tcpdf` | Packagist | All versions | 6.8.0 |

Products: Tcpdf Project Tcpdf.

## How do I fix CVE-2024-56521?

Upgrade tecnickcom/tcpdf to 6.8.0 or later.

## Is CVE-2024-56521 being exploited?

There is no known exploitation of CVE-2024-56521 in the wild and no public exploit code.

## Other vulnerabilities in tecnick tcpdf

- [CVE-2024-56519](https://insights.sbomify.com/CVE-2024-56519/): TCPDF lacks SVG sanitization (high 7.5)
- [CVE-2024-56522](https://insights.sbomify.com/CVE-2024-56522/): TCPDF has incorrect comparison (high 7.5)
- [CVE-2024-56527](https://insights.sbomify.com/CVE-2024-56527/): TCPDF missing character escape on error messages (high 7.5)
- [CVE-2024-22641](https://insights.sbomify.com/CVE-2024-22641/): Denial of service in n/a (high 7.5)
- [CVE-2017-6100](https://insights.sbomify.com/CVE-2017-6100/): Server-side request forgery in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-56521 and fix it if it is affected.

What it is: CVE-2024-56521 is a critical vulnerability in tecnick tcpdf, published on 27 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-56521 in the wild and no public exploit code.

Affected packages and fixed versions:
- tecnickcom/tcpdf (Packagist): affected all versions; fixed in 6.8.0
- tecnickcom/tcpdf (Packagist): affected all versions; fixed in 6.8.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-56521/ (Markdown: https://insights.sbomify.com/CVE-2024-56521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56521
- OSV: https://osv.dev/vulnerability/CVE-2024-56521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56521/
Summaries are generated and may contain mistakes; the official description above is the record.