CVE-2026-62439

Executive Summary

CVE-2026-62439 is an integer overflow (CWE-190) in GIMP's file-pvr plug-in, triggered when calculating memory buffer sizes for image dimensions while processing a malicious PowerVR (.pvr) file. An attacker can socially engineer a user into opening or previewing a crafted .pvr file, causing a heap-based buffer overflow that may lead to arbitrary code execution in the context of the user or, more simply, an application crash (Denial of Service). The vulnerability carries a CVSS 3.1 base score of 7.0 (High) and affects any GIMP installation that can open PVR files via the plug-in; no public PoC or active exploitation is currently known.

Technical Analysis

The flaw resides in the PVR import path of GIMP's file-pvr plug-in. PowerVR (.pvr) files are container formats for texture data, and their headers carry image dimension fields that the plug-in parses to compute the size of a destination buffer prior to decompression or pixel decoding. CVE-2026-62439 is an integer overflow in that size calculation: when image dimensions are supplied with values that cause the multiplication (or equivalent arithmetic) used to derive buffer size to wrap, the resulting allocation is smaller than the amount of data subsequently written. This produces a classic heap-based buffer overflow.

Mapping to CWE-190 is direct and consistent with the described mechanism: an arithmetic operation produces a result that exceeds the range of the target integer type, wrapping to an undersized value. The downstream consequence — a heap buffer overflow — means an out-of-bounds write past the end of the undersized heap allocation. In a memory-unsafe language context (GIMP's plug-ins are typically written in C), such an out-of-bounds write can corrupt adjacent heap metadata or objects, enabling control-flow hijack or targeted data corruption, and at minimum causing a deterministic crash.

The attack surface is the file import/preview path. GIMP renders thumbnails and previews for files in file browsers and its own open dialog, meaning a user need not deliberately "run" anything — merely browsing to a directory containing a malicious .pvr (or opening it) is sufficient to reach the vulnerable parsing code. The CVSS vector reflects this: AV:L (local, since the file must be delivered to and opened on the target host), AC:H (high attack complexity — reliable heap exploitation requires defeating modern mitigations and grooming heap state), PR:N (no privileges required), and UI:R (user interaction required to open or preview the file). Confidentiality, integrity, and availability are all rated High (C:H/I:H/A:H), consistent with arbitrary code execution potential and application crash.

No CNA title, affected version list, or function-level detail is included in the source data. The description is sufficient to establish the vulnerability class (integer overflow → heap overflow in a file parser) but does not expose specific internal functions, symbols, or file offsets, so this report does not assert them.

Exploitation Scenarios

No public proof-of-concept, exploit code, or Nuclei template exists for CVE-2026-62439. The following chain is inferred strictly from the vulnerability class and the NVD description.

1. Reconnaissance / targeting. The attacker identifies targets that use GIMP for image editing and are likely to receive image assets from untrusted sources — designers, marketing teams, game developers working with PowerVR texture assets, and CTF/security practitioners. Because GIMP is desktop software, delivery is not network-facing; the attacker instead targets individuals or shared asset pipelines.

2. Weaponization and delivery. The attacker crafts a PowerVR (.pvr) file whose header supplies image dimensions chosen so that the plug-in's buffer-size arithmetic overflows and wraps to a small value. The crafted file is delivered via phishing attachment, a shared drive or asset repository, a public file-sharing link, or a compromised download — any channel through which a victim might open or preview the file in GIMP.

3. Trigger. The victim opens the .pvr file in GIMP, or the plug-in is invoked to generate a preview/thumbnail when the file is browsed. On import, the undersized buffer is allocated and the decoded pixel data is written past its bounds, producing the heap-based buffer overflow. Achieving code execution from this point requires heap grooming and mitigation bypass (hence the High attack-complexity rating); a crash and denial of service is the straightforward outcome.

4. Post-exploitation impact. If exploitation succeeds, the attacker gains code execution at the victim's privilege level on the workstation — enabling data theft (source assets, credentials, documents accessible to the user), persistence, and lateral movement from a designer or developer workstation into shared repositories. In the more common failure mode, the crash causes loss of unsaved work and availability disruption. No in-the-wild exploitation is currently evidenced.

Impact Assessment

CVE-2026-62439 rates 7.0 (High) on CVSS 3.1 (CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H).

• Confidentiality: High. Successful memory corruption in a desktop image editor exposes files and data accessible to the logged-in user.
• Integrity: High. Out-of-bounds writes may corrupt heap state and, if exploited, permit code execution and modification of user data.
• Availability: High. The crash outcome reliably terminates the application, causing denial of service and unsaved-work loss.
• Scope: Unchanged. The overflow affects the same security authority as the application.

The blast radius is limited to hosts where a user opens the malicious file (local attack vector, user interaction required), but the population at risk — anyone using GIMP to view untrusted image assets — is broad. No CISA KEV listing, no EPSS score (not yet assigned by FIRST.org), and no known active campaigns are recorded. The patch status is a single-source (Debian) claim at confidence 2/4 and should be treated as unconfirmed until the upstream GIMP fix and version are verified.

Detection Guidance

Sigma Rule

title: GIMP file-pvr Plug-in Crash Indicative of CVE-2026-62439 Exploitation
id: 3c9f2a71-8d14-4b6e-9a2c-gimp62439pvr0001
status: experimental
description: Detects abnormal termination of GIMP's PVR plug-in process consistent with a heap overflow triggered by a crafted PowerVR (.pvr) file.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-62439
author: threat-intel
date: 2026/01/01
logsource:
  category: process_creation
  product: windows
detection:
  selection_plugin:
    Image|endswith:
      - '\file-pvr.exe'
      - '\file-pvr'
  selection_gimp_parent:
    ParentImage|endswith:
      - '\gimp-2.10.exe'
      - '\gimp-3.0.exe'
      - '\gimp.exe'
  condition: selection_plugin and selection_gimp_parent
  fields:
    - Image
    - ParentImage
    - CommandLine
    - User
  timeframe: 5m
falsepositives:
  - Legitimate loading of valid PowerVR texture files
level: low
tags:
  - attack.t1204.002
  - cve.2026.62439

YARA Rule

rule CVE_2026_62439_PVR_IntegerOverflow_Header
{
    meta:
        description = "Detects PowerVR (.pvr) files with extreme dimension fields suggestive of an integer-overflow heap-buffer-overflow attempt against GIMP file-pvr (CVE-2026-62439)"
        author = "threat-intel"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-62439"
        cve = "CVE-2026-62439"
        date = "2026-01-01"

    strings:
        $pvr_magic = { 50 56 52 03 }        // PVR v3 container magic "PVR\x03"
        $pvr_magic_v2 = { 34 12 34 12 }     // PVR v2 little-endian magic 0x12341234
        $pvr_ext = ".pvr" ascii nocase

    condition:
        ($pvr_magic at 0 or $pvr_magic_v2 at 0) and
        filesize < 100MB and
        // flag oversized declared dimensions typical of overflow-triggering headers
        uint32(0) == 0x03525650 and
        (uint32(12) > 0x0000FFFF or uint32(16) > 0x0000FFFF)
}

Suricata IDS Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"CVE-2026-62439 GIMP file-pvr PowerVR Container Download"; flow:established,to_client; file_data; content:"PVR"; depth:3; content:"|03|"; within:1; filemagic:"PowerVR"; filestore; classtype:attempted-user; reference:cve,2026-62439; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-62439; sid:2026624390; rev:1;)

Elastic Detection

process where event.type == "start" and
  process.parent.name : ("gimp-2.10.exe", "gimp-3.0.exe", "gimp.exe") and
  process.name : ("file-pvr.exe", "file-pvr")

Splunk SPL Query

index=endpoint sourcetype=WinEventLog:Security OR sourcetype=sysmon EventCode=1
| search (Image="*\\file-pvr.exe" OR Image="*\\file-pvr")
| eval parent=ParentImage
| where match(parent, "(?i)gimp.*\.exe$")
| table _time, host, User, parent, Image, CommandLine
| sort - _time

Wazuh OSSEC Rule

<group name="gimp,cve-2026-62439,">
  <rule id="2026624" level="6">
    <if_sid>61603</if_sid>
    <field name="win.eventdata.parentImage">gimp.*\.exe$</field>
    <field name="win.eventdata.image">file-pvr(\.exe)?$</field>
    <description>CVE-2026-62439: GIMP file-pvr plug-in invoked on potentially malicious PowerVR file (possible heap overflow attempt)</description>
    <mitre>
      <id>T1204.002</id>
    </mitre>
    <group>attack,user_execution,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 2/4 — CLAIMED: a single source (Debian) indicates a patch exists, but the upstream GIMP advisory and the fixed version are not confirmed in the provided data. Treat patch status as unverified and validate independently before closing the exposure.

1. Immediate mitigations. Restrict opening of untrusted .pvr files. Remove or disable the file-pvr plug-in from GIMP's plug-ins directory where PowerVR support is not operationally required. Disable thumbnail/preview generation for untrusted directories in the OS file manager to prevent silent triggers. Apply endpoint controls to block .pvr files arriving via email or download from untrusted sources. Segment high-value workstations processing external design assets.

2. Patch / upgrade steps. Monitor the GIMP project's official release and security advisories for the fixed version addressing CVE-2026-62439. Where distributions (e.g., Debian) ship patched packages, prioritize updating GIMP and its plug-in packages from the vendor repository. Confirm the fix by cross-referencing the GIMP advisory rather than relying on the single-source claim; until confirmed, keep the mitigation in step 1 in place.

3. Long-term hardening. Adopt a software inventory practice covering desktop image and design tools. Where practical, run GIMP in a sandboxed or containerized environment for processing untrusted media. Enable application-level exploit mitigations (ASLR, DEP, heap hardening) and endpoint detection for plug-in crash telemetry, which is a useful leading indicator of attempted exploitation. Track CWE-190 parsing defects across the media-processing toolchain.

References

• NVD — CVE-2026-62439: https://nvd.nist.gov/vuln/detail/CVE-2026-62439
• MITRE CWE-190 — Integer Overflow or Wraparound: https://cwe.mitre.org/data/definitions/190.html
• MITRE ATT&CK T1204.002 — User Execution: Malicious File: https://attack.mitre.org/techniques/T1204/002/
• Debian Security Tracker — CVE-2026-62439 (single-source patch claim; unconfirmed): https://security-tracker.debian.org/tracker/CVE-2026-62439
• GIMP project security advisories and release notes (verify vendor fix version): https://www.gimp.org/

No CISA KEV entry, no public PoC, and no recorded threat-actor campaigns or in-the-wild exploitation are associated with CVE-2026-62439 at time of writing.