# CVE-2018-18688: Security feature bypass in n/a

> Attackers can bypass PDF signature validation by using incremental saving to add malicious content, affecting multiple PDF reader applications.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Jan 2021
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-q966-hp9v-pw89

## What is CVE-2018-18688?

CVE-2018-18688 is a medium-severity vulnerability in Foxitsoftware Foxit Reader, published on 7 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Portable Document Format (PDF) specification does not provide any information regarding the concrete procedure of how to validate signatures. Consequently, an Incremental Saving vulnerability exists in multiple products. When an attacker uses the Incremental Saving feature to add pages or annotations, Body Updates are displayed to the user without any action by the signature-validation logic. This affects Foxit Reader before 9.4 and PhantomPDF before 8.3.9 and 9.x before 9.4. It also affects LibreOffice, Master PDF Editor, Nitro Pro, Nitro Reader, Nuance Power PDF Standard, PDF Editor 6 Pro, PDFelement6 Pro, PDF Studio Viewer 2018, PDF Studio Pro, Perfect PDF 10 Premium, and Perfect PDF Reader.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2018-18688?

It affects 13 products.


Products: Code-Industry Master Pdf Editor, Foxitsoftware Foxit Reader, Foxitsoftware Phantompdf, Gonitro Nitro Pro, Gonitro Nitro Reader, Iskysoft Pdf Editor 6, Iskysoft Pdfelement6, Libreoffice Libreoffice, Nuance Power Pdf Standard, Qoppa Pdf Studio, Qoppa Pdf Studio Viewer 2018, Soft-Xpansion Perfect Pdf 10, Soft-Xpansion Perfect Pdf Reader.

## How do I fix CVE-2018-18688?

No fix has been published for CVE-2018-18688 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-18688 being exploited?

There is no known exploitation of CVE-2018-18688 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-18688 and fix it if it is affected.

What it is: CVE-2018-18688 is a medium-severity vulnerability in Foxitsoftware Foxit Reader, published on 7 Jan 2021. 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-2018-18688 in the wild and no public exploit code.

Affected product: Foxitsoftware Foxit Reader. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2018-18688/ (Markdown: https://insights.sbomify.com/CVE-2018-18688/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-18688
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-18688
- OSV: https://osv.dev/vulnerability/CVE-2018-18688

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-18688/
Summaries are generated and may contain mistakes; the official description above is the record.