CVE-2026-24869 Overview
CVE-2026-24869 is a use-after-free vulnerability [CWE-416] in the Layout: Scrolling and Overflow component of Mozilla Firefox. The flaw allows attackers to trigger memory corruption by manipulating layout objects that have already been freed. Mozilla addressed the issue in Firefox 147.0.2, as documented in Mozilla Security Advisory MFSA-2026-06.
Exploitation requires a victim to visit a malicious or compromised web page. Successful exploitation can corrupt memory and may lead to arbitrary code execution within the browser process.
Critical Impact
A network-based attacker can leverage a freed layout object to corrupt browser memory, potentially leading to arbitrary code execution after a user loads a crafted web page.
Affected Products
- Mozilla Firefox versions prior to 147.0.2
- Firefox installations on Windows, macOS, and Linux
- Any deployment running the vulnerable Layout: Scrolling and Overflow component
Discovery Timeline
- 2026-01-27 - CVE-2026-24869 published to NVD
- 2026-04-13 - Last updated in NVD database
Technical Details for CVE-2026-24869
Vulnerability Analysis
The vulnerability resides in the Layout: Scrolling and Overflow component of Gecko, the Firefox rendering engine. This component manages scrollable frames, overflow regions, and the lifecycle of associated layout objects during page rendering.
A use-after-free condition occurs when the code accesses memory after the underlying object has been deallocated. In browser engines, these flaws frequently arise during reflows, scroll updates, or DOM mutations that invalidate cached pointers to layout frames.
Attackers can shape heap layout through JavaScript and trigger the freed-object access at a controlled moment. The resulting memory corruption can be steered toward control-flow hijack and code execution inside the content process.
Root Cause
The root cause is improper object lifetime management within the scrolling and overflow layout code. A reference to a layout object is retained and dereferenced after the object has been freed, satisfying the conditions for [CWE-416]. Technical specifics are tracked in Mozilla Bug Report #2008698, which remains access-restricted pending broad patch deployment.
Attack Vector
Exploitation requires user interaction: the victim must load attacker-controlled web content. No authentication or prior access is needed, and the attack is delivered over the network through standard HTTP or HTTPS. A crafted page can manipulate the DOM and scroll containers to free a layout object while a stale pointer is still in use, then spray the heap to gain control over the freed allocation.
Refer to Mozilla Security Advisory MFSA-2026-06 for vendor-confirmed exploitation context. No public proof-of-concept code has been released at the time of writing.
Detection Methods for CVE-2026-24869
Indicators of Compromise
- Firefox content process crashes with signatures referencing nsIFrame, scroll frame, or overflow layout code paths.
- Unexpected Firefox child process terminations correlated with visits to untrusted web pages.
- Outbound connections from firefox.exe to newly registered or low-reputation domains immediately preceding a crash event.
Detection Strategies
- Inventory installed Firefox versions across managed endpoints and flag any instance below 147.0.2.
- Monitor browser telemetry and crash reports for repeated faults inside the layout subsystem, which can indicate exploitation attempts.
- Correlate web proxy logs with endpoint process events to identify users who loaded suspicious content prior to browser crashes.
Monitoring Recommendations
- Enable EDR visibility for Firefox child process creation, module loads, and unexpected child process spawns from firefox.exe.
- Forward browser crash dumps and Windows Error Reporting events to a central log store for analyst review.
- Track URL categories and TLS metadata from corporate browsers to identify high-risk navigations preceding crash indicators.
How to Mitigate CVE-2026-24869
Immediate Actions Required
- Update all Firefox installations to version 147.0.2 or later as published in Mozilla Security Advisory MFSA-2026-06.
- Push the updated build through enterprise management tooling and verify completion across managed endpoints.
- Restart Firefox after patching to ensure the vulnerable code is unloaded from running processes.
Patch Information
Mozilla fixed CVE-2026-24869 in Firefox 147.0.2. Administrators should consult Mozilla Security Advisory MFSA-2026-06 for the complete list of addressed issues and download channels. Extended Support Release (ESR) users should verify their channel includes the corresponding fix.
Workarounds
- Restrict browsing on unpatched endpoints to trusted internal sites until the update is applied.
- Disable JavaScript on untrusted origins through enterprise policy or browser extensions to reduce the attacker's ability to shape heap layout.
- Apply web filtering at the proxy or DNS layer to block known malicious domains and reduce exposure to drive-by content.
# Verify the installed Firefox version on Linux/macOS
firefox --version
# Windows: query installed version from the registry
reg query "HKLM\SOFTWARE\Mozilla\Mozilla Firefox" /v CurrentVersion
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
