CVE-2026-77219

A flaw was found in GNU Emacs. An integer overflow in the PBM/PPM/PGM image loader allows a remote attacker to leak heap memory contents. By supplying a specially crafted image with large dimensions and an elevated maximum color index, the image loader's internal calculations can wrap to a negative number, bypassing memory bounds checks. This enables the pixel reader to access and render sensitive information from heap memory.

This vulnerability is rated as an Important severity flaw because rendering a specially crafted bitmap file can allow an attacker to disclose sensitive heap memory or trigger an application crash, potentially exposing confidential data from active editor buffers. Although successful exploitation requires user interaction to open or view a malicious image file, the potential compromise of co-located session data elevates the security impact above Moderate. In standard Red Hat Enterprise Linux deployments, exposure is primarily limited to interactive graphical desktop environments where Emacs processes untrusted external files.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, users should avoid opening or displaying untrusted PBM, PPM, or PGM image files within GNU Emacs. Exercise caution when handling image files from unknown or unverified sources.