CVE-2026-4455: 
vulnerability analysis and mitigation

CVE-2026-4455 is a heap buffer overflow vulnerability in the PDFium component of Google Chrome that allows a remote attacker to potentially exploit heap corruption via a crafted PDF file. It affects all Google Chrome versions prior to 146.0.7680.153, as well as Microsoft Edge (Chromium-based). The vulnerability was reported by researcher c6eed09fc8b174b0f3eebedcceb1e792 on March 1, 2026, and publicly disclosed on March 18–20, 2026, when Google released Chrome 146.0.7680.153 (Chrome Releases). It carries a CVSS v3.1 base score of 8.8 (High) (Feedly).

The vulnerability is classified as CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write), rooted in insufficient bounds checking within Chrome's PDFium PDF rendering library (Feedly). An attacker can exploit this by delivering a specially crafted PDF file to a victim; when the file is opened in a vulnerable Chrome browser, the malformed content triggers a heap buffer overflow during PDF parsing or rendering, leading to out-of-bounds write operations in heap memory. Exploitation requires user interaction (opening the malicious PDF) but no authentication or special privileges, and the attack is delivered over the network (Feedly). The Chromium issue tracker references bug ID 488585504 for this vulnerability (Chrome Releases).

Successful exploitation can result in arbitrary code execution with the privileges of the Chrome browser process, impacting confidentiality, integrity, and availability at HIGH severity across all three categories. An attacker who tricks a user into opening a malicious PDF could gain control of the browser process, potentially enabling data theft, installation of malware, or further lateral movement within the victim's environment (Feedly). The scope is limited to the affected browser process (sandbox escape would require a separate vulnerability), but the heap corruption primitive is a strong foundation for reliable exploitation.

1. Craft a malicious PDF: Create a specially crafted PDF file that triggers a heap buffer overflow in Chrome's PDFium rendering library during parsing or rendering of specific PDF structures (e.g., malformed stream objects, font data, or image resources).
2. Deliver the payload: Host the malicious PDF on an attacker-controlled web server or distribute it via email, messaging platforms, or file-sharing services to potential victims.
3. Social engineering: Lure the target into opening the PDF in a vulnerable Chrome browser (prior to version 146.0.7680.153) — for example, via a phishing email with a link or attachment.
4. Trigger heap corruption: When Chrome's PDFium component processes the malformed PDF, the heap buffer overflow occurs, corrupting adjacent heap memory with attacker-controlled data.
5. Achieve code execution: Leverage the out-of-bounds write to overwrite heap metadata or function pointers, redirecting execution flow to attacker-controlled shellcode or a ROP chain, resulting in arbitrary code execution within the Chrome renderer process (Chrome Releases, Feedly).

• Network: Unexpected outbound connections from the Chrome browser process to unknown external IP addresses or domains following the opening of a PDF file; HTTP/HTTPS requests to download secondary payloads after PDF rendering.
• Process: Unusual child processes spawned by the Chrome renderer process (e.g., cmd.exe, powershell.exe, bash, curl, wget); Chrome renderer process crashing with heap corruption errors in crash logs.
• File System: Unexpected files written to the user's temp directory or Chrome profile directory following PDF viewing; new executables or scripts created by the Chrome process.
• Logs: Chrome crash reports or Windows Event Logs showing access violations or heap corruption exceptions originating from PDFium-related modules; browser crash dumps referencing pdfium.dll or equivalent shared library.

Google has patched this vulnerability in Chrome version 146.0.7680.153 (Linux) and 146.0.7680.153/154 (Windows/Mac); all users should update immediately via Chrome's built-in update mechanism (Chrome Releases). Microsoft Edge (Chromium-based) users should apply the corresponding Edge update referenced in the Microsoft Security Response Center advisory (Microsoft). As an interim workaround, organizations can restrict users from opening PDF files from untrusted sources in Chrome, or configure Chrome to download PDFs rather than rendering them inline. Linux distributions including Debian, Fedora, and openSUSE have also released updated Chromium packages (Feedly).

The vulnerability was part of a broader Chrome security update that fixed 26 vulnerabilities, which received coverage from multiple security news outlets including GBHackers, CyberSecurityNews, and CyberPress, highlighting the significance of the release (Feedly). Community discussion on Mastodon and Infosec.exchange noted the high number of high-severity fixes in this Chrome release. Red Hat tracked the issue via Bugzilla (Bug 2449392) and classified it as high priority/severity (Red Hat Bugzilla). Palo Alto Networks also issued a security advisory (PAN-SA-2026-0007) referencing this CVE in the context of their Chromium-based products (Feedly).