fkie_cve-2026-115924

Rembg is a tool to remove images background. Prior to 2.0.82, the public /api/remove endpoint passes attacker-controlled extras.sam_model through rembg/commands/s_command.py to rembg/sessions/sam.py, where it is interpolated into SAM filenames and GitHub download URLs passed to pooch.retrieve() without a pinned hash. An unauthenticated attacker can supply a sam_model value combining path traversal with URL fragment syntax to exploit the HTTP request discarding the fragment while the local POSIX path retains it. The first request primes the attacker-selected path tree, and an identical repeated request downloads malicious ONNX encoder and decoder files beside a readable target file. The graphs can load the target through ONNX external data and encode its bytes into the returned PNG mask, disclosing complete files accessible to the rembg process and allowing arbitrary ONNX computation. This issue is fixed in version 2.0.82.

GHSA-qr6x-7v33-6qmg — Rembg: Unauthenticated SAM model injection permits local-file disclosure through malicious ONNX graphs

Affected: PyPI: rembg

The public `/api/remove` endpoint uses attacker-controlled `extras.sam_model` in both SAM filenames and GitHub download URLs. Path traversal plus a URL fragment lets an unauthenticated attacker place malicious ONNX models beside a target file. The models read the file as ONNX external data and encode its bytes into the returned PNG.

This issue affects SAM's `sam_model` in 2.0.81 and returns complete file contents.

*Screenshot 1 — First unauthenticated request primes the path and returns HTTP 500.*

### Technical details

`rembg/commands/s_command.py:188-223,384-397` accepts public `extras` JSON and passes it to `new_session()`. `rembg/sessions/sam.py:313-355` inserts `sam_model` into encoder/decoder filenames and fixed GitHub URLs, then invokes `pooch.retrieve()` without a pinned hash.

Requests removes the URL `#fragment`; the local POSIX path retains it. Pooch creates attacker-selected parent directories without enforcing cache containment. The first request creates the path tree and returns HTTP 500. The identical second request downloads the attacker asset twice and stores it as both SAM models beside the target.

The graph uses a relative external tensor to read the target and maps every byte to mask pixels. rembg returns the mask as a PNG, which the attacker decodes back into the original bytes.

<img width="2432" height="1254" al…

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fkie_cve-2026-115924

GHSA-qr6x-7v33-6qmg — Rembg: Unauthenticated SAM model injection permits local-file disclosure through malicious ONNX graphs