CVE-2026-91733 in Chrome
Summary
by MITRE • 09/15/2026
Improper state validation in Skia in Google Chrome prior to 153.0.8010.47 allowed a remote attacker who had compromised the renderer process to read memory outside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified as an improper state validation flaw within the Skia graphics library, which is integrated into Google Chrome prior to version 153.0.8010.47, represents a significant breach in browser sandboxing mechanisms. This issue arises from inadequate checks on internal data structures during rendering operations, allowing for out-of-bounds memory access when processing maliciously crafted HTML content. The core technical flaw lies in the failure of Skia to properly validate state transitions or buffer boundaries before executing graphics commands, which creates a window where an attacker can manipulate pointer arithmetic or array indices to read from arbitrary memory locations outside the designated sandboxed renderer process space.
From a security architecture perspective, this vulnerability undermines the critical isolation model that separates untrusted web content from sensitive system resources and user data. By exploiting improper state validation, a remote attacker who has already compromised the renderer process through initial vectors such as cross-site scripting or drive-by downloads can escalate their privileges within the browser environment. The ability to read memory outside the sandbox enables the extraction of sensitive information including cookies, session tokens, passwords stored in autofill fields, and potentially cryptographic keys used by other tabs or extensions running under different security contexts. This effectively breaks the trust boundary that Chrome enforces between renderer processes and the main browser process.
The operational impact of this vulnerability is severe due to its potential for remote code execution precursors and data exfiltration. Although the description specifies memory reading rather than direct write access, out-of-bounds reads are often a precursor to more complex exploitation chains involving information disclosure followed by heap grooming or type confusion attacks that lead to arbitrary read-write primitives. Attackers can leverage this flaw to fingerprint browser internals, bypass security mitigations such as ASLR and DEP, and gather intelligence necessary for further lateral movement within the victim's system. The severity rating of High reflects the ease with which this state validation error can be triggered via standard web technologies like HTML and JavaScript without requiring user interaction beyond visiting a malicious webpage.
In terms of industry standards classification, this vulnerability aligns closely with CWE-125 Out-of-bounds Read, as it involves accessing memory locations that are not allocated to the requesting process or object. Furthermore, from an offensive security framework perspective such as MITRE ATT&CK, this behavior corresponds to techniques related to Process Injection and Data Staged for Exfiltration over C2 Channels, specifically leveraging browser-based execution environments to bypass traditional endpoint detection systems. The exploitation path typically involves crafting specific SVG or canvas elements that trigger the flawed Skia code paths during rasterization or compositing phases of rendering.
Mitigation strategies primarily involve updating Google Chrome to version 153.0.8010.47 or later, where these state validation checks have been hardened and boundary conditions are rigorously enforced within the Skia library. For organizations unable to immediately patch all endpoints, network-level controls such as web application firewalls can be configured to detect and block requests containing suspiciously crafted HTML structures known to trigger this specific rendering bug. Additionally, enabling Chrome’s site isolation features more aggressively can limit the blast radius of any successful renderer compromise by ensuring that cross-site data is never accessible even if a sandbox escape occurs within a single tab context. Regular security audits focusing on third-party library integration points and continuous monitoring for anomalous memory access patterns in browser processes are recommended to detect potential exploitation attempts before they result in significant data loss or system compromise.