CVE-2026-59088: GIMP Integer Overflow DoS Vulnerability

CVE-2026-59088 Overview

CVE-2026-59088 is a signed integer overflow vulnerability in the GNU Image Manipulation Program (GIMP), specifically within the file-fli plugin that parses FLI animation files. The flaw occurs during memory allocation for image buffers, where the multiplication of image width and height can exceed the maximum value of a signed integer. A remote attacker can craft a malicious FLI file that triggers the overflow when opened, causing the application to crash. The issue is tracked under CWE-190: Integer Overflow or Wraparound and requires local file access with user interaction.

Critical Impact
A specially crafted FLI file opened in GIMP causes an application crash, resulting in denial of service and potential loss of unsaved work.

Affected Products

GIMP (GNU Image Manipulation Program) — file-fli plugin
Linux distributions packaging vulnerable GIMP builds (see Red Hat CVE-2026-59088 Advisory)
Downstream applications and workflows that embed the GIMP FLI parser

Discovery Timeline

2026-08-10 - CVE-2026-59088 published to the National Vulnerability Database
2026-08-11 - Last updated in the NVD database

Technical Details for CVE-2026-59088

Vulnerability Analysis

The vulnerability resides in the FLI import path of GIMP's file-fli plugin. FLI is a legacy Autodesk animation format that stores raw pixel dimensions in its header. When GIMP parses an FLI file, it computes the required buffer size by multiplying the reported width and height. Because both operands are treated as signed integers, an attacker-controlled combination can wrap past INT_MAX and produce a small or negative allocation size. The plugin then writes decoded frame data based on the original attacker-supplied dimensions, but into an undersized buffer, corrupting adjacent memory and terminating the process.

Root Cause

The root cause is missing bounds validation on width and height fields prior to the buffer size calculation, classified as CWE-190. The plugin trusts header values without checking that width * height * bytes_per_pixel fits within the target integer type. Additional context is available in the GNOME GIMP Work Item #16492 and the Red Hat Bug Report #2496582.

Attack Vector

Exploitation requires an attacker to deliver a malicious FLI file to a victim and convince them to open it in GIMP. Common delivery methods include phishing emails with FLI attachments, malicious downloads, or shared design assets. No authentication or elevated privileges are required beyond the victim's own user session. The observed impact is a process crash; the referenced advisories describe the result as denial of service rather than code execution.

No verified proof-of-concept code is publicly available. The vulnerability mechanism is described in prose above; consult the Red Hat CVE-2026-59088 Advisory for further technical details.

Detection Methods for CVE-2026-59088

Indicators of Compromise

Unexpected GIMP process crashes correlated with opening .fli or .flc files
Presence of FLI files from untrusted sources in user download or attachment directories
Core dumps or crash reports referencing the file-fli plugin within GIMP's plug-in directory

Detection Strategies

Enable and collect application crash telemetry (e.g., systemd-coredump, ABRT, Windows Error Reporting) and alert on repeated GIMP faults
Inspect FLI file headers at ingress and flag files with implausibly large width or height fields that would overflow standard buffer arithmetic
Correlate GIMP crash events with recent file-open activity for .fli and .flc extensions to identify targeted delivery

Monitoring Recommendations

Track GIMP package versions across managed hosts and prioritize systems still running builds prior to the vendor fix
Monitor email gateways and file-sharing platforms for FLI attachments, which are uncommon in modern workflows
Aggregate endpoint crash events into a central SIEM to detect patterns consistent with exploitation attempts against creative workstations

How to Mitigate CVE-2026-59088

Immediate Actions Required

Apply vendor-supplied GIMP updates as soon as they are available from your distribution, per the Red Hat CVE-2026-59088 Advisory
Instruct users not to open FLI or FLC files received from untrusted sources until patches are deployed
Restrict file-association handlers so that FLI files do not open in GIMP automatically from mail clients or browsers

Patch Information

Refer to the GNOME GIMP Work Item #16492 for upstream fix tracking and the Red Hat Bug Report #2496582 for downstream package status. Distribution maintainers are expected to ship updated GIMP packages that add bounds validation to the file-fli plugin's allocation logic. Apply updates through your standard package manager once released.

Workarounds

Disable or remove the file-fli plugin from the GIMP plug-in directory if FLI support is not required in your environment
Block .fli and .flc attachments at the email gateway and web proxy where feasible
Route untrusted image files through a sandboxed conversion workflow before allowing them onto analyst workstations

bash

# Example: remove the file-fli plugin on a Linux system where FLI import is not needed
# Adjust the path to match your distribution's GIMP plug-in directory
sudo rm /usr/lib64/gimp/2.0/plug-ins/file-fli/file-fli

# Verify GIMP no longer registers the FLI importer
gimp -i -b '(car (gimp-version))' -b '(gimp-quit 0)'