Out-of-bounds Read in GNU Emacs
CVE-2026-77219
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H.
EPSS exploit prediction
EPSS: 0.001 (2.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 2.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
Weakness classification (CWE)
References
- debbugs.gnu.org/cgi/bugreport.cgi (issue-tracking)
- github.com/emacs-mirror/emacs/releases/tag/emacs-31.0.91 (release-notes)
- github.com/emacs-mirror/emacs/commit/b07e634e4cf45162ae0178e32092b040587f2c6c (patch)
- www.vulncheck.com/advisories/gnu-emacs-heap-over-read-via-pbm-ppm-pgm-image-loa… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-77219?
- CVE-2026-77219 is a high-severity vulnerability in GNU Emacs, classified under Out-of-bounds Read. CVSS score: 7.1/10. Published 2026-08-21.
- How severe is CVE-2026-77219?
- High severity. CVSS v3 base score is 7.1 out of 10.