**CRITICAL RISK** CVE-2023-4863 LibWebP – Heap-Based Buffer Overflow Vulnerability

Background & Context

WebP is a modern image format that provides superior lossless and lossy compression for images on the web.


Vulnerability Summary

A heap-based buffer overflow vulnerability exists in WebP. Exploit of the vulnerability would involve a remote attacker triggering an out of bounds memory write via a crafted HTML page.

A buffer overflow condition exists when a product attempts to put more data in a buffer than it can hold, or when it attempts to put data in a memory area outside of the boundaries of a buffer. The simplest type of error, and the most common cause of buffer overflows, is the “classic” case in which the product copies the buffer without restricting how much is copied. Other variants exist, but the existence of a classic overflow strongly suggests that the programmer is not considering even the most basic of security protections.


Impact If Exploited

Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of the product’s implicit security policy. This can often be used to subvert any other security service. Google has decided to not provide further information about the zero-day vulnerability until the majority of users have applied the updates.

NOTE: This vulnerability has been reported by the CISA (America’s Cyber Defense Agency) to be known to be currently actively exploited in the wild as of 2023-09-14. Remediation should therefore be considered as a priority in any impacted environments.

Affected Product Versions

  • Google Chrome for Mac and Linux prior to release 116.0.5845.187
  • Google Chrome for Windows prior to release 116.0.5845.187/.188

NOTE: Google requested a second CVE (CVE-2023-5129) once it became clear that this vulnerability was not restricted to Chrome only, but it was rejected as a duplicate

Other common Linux applications contain or use the vulnerable libvpx package as a dependency. Examples include: gstreamer1-plugins-good, gstreamer-plugins-bad-free, ffmpeg-libs, libgd3, Microsoft vcpkg, Telegram and Telegram Desktop, FFmpeg, SmartTubeLegacy, Openai Retro, Google ExoPlayer, Natron. Additional affected products may also include 1Password, FireFox Chrome, GitHub Desktop, Safari, Signal, Twitch.



Official Fix & Remediation Guidance

Chrome users are advised to update to version 116.0.5845.187 for Mac and Linux devices, and 116.0.5845.187/.188 for Windows devices to avoid the exploitation of the vulnerability. The new version is currently rolling out to users in the Stable and Extended stable channels. This update was immediately available when checked for new updates via the Chrome menu > Help > About Google Chrome in testing.

Other impacted products should be checked for available patches and updates.

If it is not possible to apply mitigations per vendor instructions, consideration should be given to discontinuing use of the product if mitigations are unavailable.

NOTE: This vulnerability has been reported by the CISA (America’s Cyber Defense Agency) to be known to be currently actively exploited in the wild as of 2023-09-14. Remediation should therefore be considered as a priority in any impacted environments.

NOTE: Remediation of this vulnerability by patching to a specific version indicated may not be sufficient to secure the product against further vulnerabilities discovered in later versions, subsequent to the publication of this guidance. Unless contra-indicated, customers are therefore advised to always upgrade to the latest version of the product available.

Temporary Mitigation & Workarounds

(The vendor has not advised of any alternative temporary mitigation or workarounds)

NOTE: Caution should always be taken in applying any temporary mitigations listed. Mitigations are only recommended in cases where patches to remediate the vulnerability are not available, or cannot safely be applied to a given environment immediately. A given mitigation may not in all cases be recommended officially by the application vendor. The viability of any given temporary mitigation measure may vary, depending on server platform and existing configuration. Mitigations listed may incompletely remediate any given vulnerability. Configuration changes to implement listed mitigations may impact/disrupt required functionality within a given customer application. Care should therefore be taken to carefully analyse any listed mitigations for appropriateness to a given environment. Customers are advised to test any configuration changes prior to their being introduced into a production environment.


Category: Buffer Overflow



AppCheck has added a plugin to detect the flaw that will run as part of your standard scans.


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