GIMP CVE-2026-18300

Exploitation requires the victim to actively open a specially crafted HDR (High Dynamic Range) image file in GIMP 3.2.2 - this is the sole mandatory condition. HDR file parsing is enabled by default in GIMP via GEGL; no non-default configuration or feature flag is required. The attack is bounded by the local execution context: the attacker cannot exploit this remotely without user interaction, and must deliver the malicious file through a social engineering vector (phishing, malicious download, or poisoned shared storage). Code execution is limited to the privileges of the current user process; no lateral privilege escalation component is identified in available data. The dependency on UI:R (per CVSS) and AV:L meaningfully limits mass automated exploitation.

The CVSS 7.8 High score is anchored by a full High triad (C:H/I:H/A:H) but meaningfully constrained by AV:L (local attack vector) and UI:R (user interaction required), meaning opportunistic mass exploitation over the network is not possible - the attacker must socially engineer the victim into opening a crafted HDR file. No EPSS score is present in the available intelligence, so probabilistic exploitation likelihood cannot be quantified from this dataset. The absence of KEV listing and confirmed public exploit code further reduces immediate urgency for most organizations, though ZDI's involvement signals that the research community has fully characterized the flaw. The dependency chain adds an important wrinkle: because the fix targets GEGL rather than GIMP directly, patch propagation through Linux distribution packaging pipelines may lag, meaning even organizations that promptly update GIMP could remain exposed if the underlying GEGL package is not simultaneously updated. The realistic target population - graphic designers, photographers, and media professionals who routinely open HDR files from external or client-supplied sources - faces a credible phishing or malicious-download scenario, and any team relying on GIMP in production image workflows should treat this as a priority patch.

An attacker crafts an HDR image file containing field values engineered to trigger an integer overflow during buffer size calculation in GEGL's HDR parser, then delivers it to a target graphic designer via email attachment, a file-sharing link, or a download prompt on a malicious webpage. When the victim opens the file in GIMP 3.2.2, the overflow produces an undersized heap allocation, enabling the attacker to overwrite adjacent memory and achieve arbitrary code execution running under the victim's user account. No public exploit code is confirmed, but ZDI's full characterization of the flaw (ZDI-CAN-29289) means the barrier to weaponization is lower than for an unanalyzed bug.