CVE-2026-77219: Integer Overflow or Wraparound in GNU Emacs
GNU Emacs before 31.0.91 contains an integer overflow in the PBM/PPM/PGM image loader that allows an attacker to leak heap memory contents by supplying a crafted image with large dimensions and an elevated max color index. The image loader multiplies image dimensions and channel count using signed integer arithmetic; for sufficiently large values, the result wraps to a negative number, bypassing the bounds check and causing the pixel reader to access heap memory past the end of the allocated buffer. The over-read contents are interpreted as pixel color values and rendered on screen.
AI Analysis
Technical Summary
CVE-2026-77219 is an integer overflow vulnerability in GNU Emacs before version 31.0.91 affecting the PBM/PPM/PGM image loader. The vulnerability arises because the image loader multiplies image dimensions and channel count using signed integer arithmetic. For sufficiently large values, this multiplication wraps to a negative number, bypassing bounds checks and causing the pixel reader to read heap memory past the allocated buffer. The leaked heap memory contents are then interpreted as pixel color values and rendered on screen, potentially exposing sensitive memory data.
Potential Impact
An attacker can cause GNU Emacs to leak heap memory contents by opening a specially crafted image file. This memory disclosure could reveal sensitive information stored in heap memory. The vulnerability does not allow code execution or privilege escalation but can compromise confidentiality by exposing internal memory data.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid opening untrusted PBM/PPM/PGM images with large dimensions or elevated max color indices in affected versions of GNU Emacs.
CVE-2026-77219: Integer Overflow or Wraparound in GNU Emacs
Description
GNU Emacs before 31.0.91 contains an integer overflow in the PBM/PPM/PGM image loader that allows an attacker to leak heap memory contents by supplying a crafted image with large dimensions and an elevated max color index. The image loader multiplies image dimensions and channel count using signed integer arithmetic; for sufficiently large values, the result wraps to a negative number, bypassing the bounds check and causing the pixel reader to access heap memory past the end of the allocated buffer. The over-read contents are interpreted as pixel color values and rendered on screen.
CVSS v4.0
Score 6.9medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-77219 is an integer overflow vulnerability in GNU Emacs before version 31.0.91 affecting the PBM/PPM/PGM image loader. The vulnerability arises because the image loader multiplies image dimensions and channel count using signed integer arithmetic. For sufficiently large values, this multiplication wraps to a negative number, bypassing bounds checks and causing the pixel reader to read heap memory past the allocated buffer. The leaked heap memory contents are then interpreted as pixel color values and rendered on screen, potentially exposing sensitive memory data.
Potential Impact
An attacker can cause GNU Emacs to leak heap memory contents by opening a specially crafted image file. This memory disclosure could reveal sensitive information stored in heap memory. The vulnerability does not allow code execution or privilege escalation but can compromise confidentiality by exposing internal memory data.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid opening untrusted PBM/PPM/PGM images with large dimensions or elevated max color indices in affected versions of GNU Emacs.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-20T18:25:46.943Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a88b714acd9273b49b41695
Added to database: 08/21/2026, 20:37:40 UTC
Last enriched: 08/21/2026, 20:52:43 UTC
Last updated: 08/21/2026, 21:52:54 UTC
Views: 4
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