CVE-2026-59087: GIMP Seattle Filmworks RCE Vulnerability

CVE-2026-59087 Overview

CVE-2026-59087 is a heap overflow vulnerability in the GNU Image Manipulation Program (GIMP), specifically within its Seattle Filmworks (SFW) file loader plugin. A remote attacker can exploit this flaw by delivering a specially crafted .sfw file and convincing a user to open it in GIMP. When parsed, the loader writes several kilobytes of attacker-controlled data past the intended heap buffer. The resulting memory corruption can lead to arbitrary code execution in the context of the GIMP process, or crash the application, causing a denial of service. The weakness is tracked as an out-of-bounds write [CWE-787].

Critical Impact
Opening a malicious Seattle Filmworks file in GIMP can corrupt heap memory and enable arbitrary code execution under the user's account.

Affected Products

GNU Image Manipulation Program (GIMP) — Seattle Filmworks file loader plugin
Linux distributions packaging vulnerable GIMP builds, including Red Hat
Any downstream product bundling the affected GIMP SFW loader

Discovery Timeline

2026-08-10 - CVE-2026-59087 published to the National Vulnerability Database (NVD)
2026-08-12 - CVE-2026-59087 last modified in NVD

Technical Details for CVE-2026-59087

Vulnerability Analysis

The flaw resides in GIMP's Seattle Filmworks image loader, a plugin that parses the proprietary .sfw format used by legacy Seattle Filmworks photo scans. The loader trusts size and offset fields embedded in the file header when allocating and populating its heap buffer. A crafted file supplies inconsistent or oversized values, causing the loader to write beyond the allocated region during image data decoding.

Because the overflow occurs on the heap and involves several kilobytes of controlled bytes, an attacker can overwrite adjacent heap metadata and application objects. This provides the primitives typically required to hijack control flow, including function pointer overwrite and heap grooming. Exploitation requires user interaction: the victim must open the malicious file with GIMP.

Root Cause

The root cause is missing validation of length and offset fields parsed from the SFW file before they are used to size and index a heap allocation. The loader treats attacker-controlled input as trusted, violating standard boundary checks associated with [CWE-787] out-of-bounds write conditions.

Attack Vector

The attack vector is local and file-based. An attacker distributes a crafted .sfw file through phishing email, a compromised website, or a shared drive. When the target opens the file in GIMP, the vulnerable plugin executes the parsing routine and triggers the overflow. No elevated privileges are required to trigger the bug, and the resulting code executes with the privileges of the user running GIMP.

No verified public proof-of-concept code is available. Technical details of the parsing flaw are described in the Red Hat CVE Advisory, the Red Hat Bug Report, and the GNOME GIMP Work Item.

Detection Methods for CVE-2026-59087

Indicators of Compromise

Unexpected .sfw files delivered through email attachments, chat platforms, or download links, particularly to users who do not routinely process Seattle Filmworks scans.
GIMP process crashes with heap corruption signatures such as SIGSEGV or glibc malloc() abort messages in system logs.
GIMP spawning child processes such as sh, bash, or python after a file-open action.

Detection Strategies

Hunt for GIMP processes performing anomalous behavior after opening image files, including network egress, shell execution, or writes to autostart locations.
Inspect endpoint telemetry for .sfw file writes originating from browsers, mail clients, or archive utilities.
Correlate GIMP crash events with recent file-open activity to identify potential exploitation attempts.

Monitoring Recommendations

Enable process lineage and file-access logging on workstations that run GIMP, and forward events to a centralized SIEM or data lake for retention and hunting.
Alert on GIMP loading libraries or executing binaries outside its normal installation footprint.
Track distribution of .sfw files across email gateways and file shares, since the format is uncommon in most enterprises.

How to Mitigate CVE-2026-59087

Immediate Actions Required

Apply vendor updates to GIMP as soon as patched packages are published by your distribution.
Restrict opening of untrusted image files, especially .sfw attachments from external senders.
Communicate the risk to users who handle image assets and reinforce phishing awareness.

Patch Information

Refer to the Red Hat CVE Advisory and the GNOME GIMP Work Item for upstream fix status and package versions. Update GIMP through the operating system package manager once fixed builds are available for your distribution.

Workarounds

Disable or remove the Seattle Filmworks plugin from the GIMP plug-ins directory (for example, file-sfw) until a patched version is installed.
Block .sfw file types at email and web gateways where the format has no legitimate business use.
Run GIMP under a standard, non-privileged user account and consider sandboxing with tools such as firejail or Flatpak's default confinement.

bash

# Locate and disable the Seattle Filmworks loader plugin (adjust path per distribution)
find /usr/lib*/gimp -type f -name 'file-sfw*' -print
sudo chmod a-x /usr/lib64/gimp/2.10/plug-ins/file-sfw/file-sfw

# Block .sfw attachments at a Postfix gateway via header_checks
echo '/name=[^\"]*\.sfw/ REJECT SFW files blocked (CVE-2026-59087)' | \
  sudo tee -a /etc/postfix/header_checks
sudo postmap /etc/postfix/header_checks && sudo systemctl reload postfix