CVE-2026-6695: GIMP PAA File Format RCE Vulnerability

CVE-2026-6695 Overview

CVE-2026-6695 is a heap-based out-of-bounds write in the GNU Image Manipulation Program (GIMP). The flaw resides in the decode_lzss() function of the Paint Shop Pro Array (PAA) file format plugin. An attacker who convinces a user to open a crafted PAA image triggers a write beyond the intended heap buffer. The condition corrupts heap metadata and can enable arbitrary code execution in the context of the GIMP process. The issue is classified under CWE-805: Buffer Access with Incorrect Length Value.

Critical Impact
Successful exploitation corrupts heap metadata during PAA image decoding and can lead to arbitrary code execution under the user account running GIMP.

Affected Products

GIMP (GNU Image Manipulation Program) — PAA file format plugin
Linux distributions shipping affected GIMP builds (see Red Hat CVE-2026-6695 Advisory)
Any downstream package that bundles the vulnerable GIMP PAA plugin

Discovery Timeline

2026-08-03 - CVE-2026-6695 published to the National Vulnerability Database
2026-08-03 - Last updated in NVD database

Technical Details for CVE-2026-6695

Vulnerability Analysis

The vulnerability exists in the PAA file format plugin GIMP uses to decode Paint Shop Pro Array images. When the plugin processes a crafted PAA file, the decode_lzss() routine writes decompressed data past the end of a heap-allocated destination buffer. The out-of-bounds write overlaps adjacent heap chunks and their allocator metadata.

An attacker who controls the compressed payload can influence both the location and content of the overflowing write. This gives the attacker a primitive to corrupt allocator bookkeeping structures, function pointers stored on the heap, or object vtables reachable from the GIMP process. Exploitation requires the victim to open the malicious PAA file locally, which aligns with the local attack vector and required user interaction described by the CVSS vector.

Root Cause

The root cause is missing or incorrect bounds validation in the LZSS decompression path of the PAA plugin. decode_lzss() does not correctly enforce the length of the destination buffer against the size implied by the compressed stream. A malformed header or oversized back-reference in the LZSS stream drives the decoder to write past the allocated region, mapping directly to CWE-805.

Attack Vector

Exploitation is file-based and requires user interaction. The attacker delivers a crafted .paa file through email, chat, a web download, or a shared file system. When the user opens the file in GIMP or previews it with a GIMP-backed thumbnailer, the PAA plugin loads and invokes the vulnerable decoder. No network exposure of GIMP is required, and no elevated privileges are needed to trigger the flaw.

No verified public exploit code is available at this time. See the Red Hat Bug Report #2459780 for additional technical detail.

Detection Methods for CVE-2026-6695

Indicators of Compromise

Unexpected .paa files arriving via email attachments, downloads, or shared drives on workstations that have GIMP installed.
GIMP process crashes, aborts from glibc heap consistency checks (for example malloc(): corrupted top size), or SIGSEGV events correlated with opening image files.
Child processes spawned from the GIMP process (gimp-2.10, gimp) that are not part of normal plugin behavior, such as shells or network clients.

Detection Strategies

Alert on GIMP processes that write to or execute from unusual paths after loading a file with a .paa extension.
Hunt for anomalous parent-child relationships where GIMP spawns interpreters (bash, sh, python), download utilities (curl, wget), or memory-mapping tools.
Correlate application crash telemetry (core dumps, systemd-coredump, ABRT events) with recent file-open activity for PAA files.

Monitoring Recommendations

Collect endpoint process and file telemetry for hosts running GIMP, including command lines and loaded modules.
Ingest Linux audit logs and core-dump events into a central data lake so heap corruption crashes are searchable across the fleet.
Track distribution package inventories to identify hosts still running unpatched GIMP versions once vendor updates are published.

How to Mitigate CVE-2026-6695

Immediate Actions Required

Inventory endpoints and multi-user servers with GIMP installed and prioritize workstations that handle untrusted image files.
Instruct users not to open PAA files from untrusted sources until distribution patches are applied.
Disable or remove the PAA file format plugin from GIMP installations that do not require Paint Shop Pro Array support.

Patch Information

Monitor the Red Hat CVE-2026-6695 Advisory and the upstream GIMP project for fixed package versions. Apply vendor updates through the distribution package manager as they become available, and rebuild any container images that bundle GIMP.

Workarounds

Remove the PAA plugin file from the GIMP plug-ins directory on systems where PAA support is not needed.
Restrict file associations so .paa files do not open in GIMP by default on shared workstations.
Run GIMP under a restricted user profile or sandbox (for example Flatpak or firejail) to limit the impact of heap corruption exploitation.

bash

# Example: locate and disable the PAA plugin on a Linux workstation
# Adjust the path for your distribution and GIMP version
find /usr/lib*/gimp -type f -iname '*paa*' -print
sudo chmod a-x /usr/lib64/gimp/2.0/plug-ins/file-paa/file-paa

# Optional: run GIMP inside a Flatpak sandbox for additional isolation
flatpak install flathub org.gimp.GIMP
flatpak run org.gimp.GIMP