high · 8.7 Patched

Pillow: MSP RLE decoder expands a tiny file into unbounded memory

CVE-2026-112892 · GHSA-gg2r-wvfm-q9rx · published 21 Oct 2026

How serious is it

  • Severity: high, CVSS score 8.7 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2026-112892?

Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.

Who is affected

  • pillow (PyPI) >= 4.1.0, < 13.0.0

How to check

  1. Run pip show pillow in your project to see the installed version, including copies pulled in by other packages.
  2. Or paste your lockfile into the checker: it lists every package with a known vulnerability, this one included.
  3. Or run npx shippable-dev scan localhost:3000 in your project folder. It reads your lockfile and flags this vulnerability along with every other known one.

How to fix

Copies a prompt for Claude Code, Cursor or Codex: it checks your lockfiles for this and upgrades it.
  1. Upgrade pillow to 13.0.0 or later, commit the lockfile and redeploy.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

### Summary The MSP RLE decoder expands run-length data into an in-memory buffer with no cap tied to the declared image size. A small file that passes the pixel-count check can force hundreds of megabytes or more of allocation when the application loads pixels. ### Details The MSP decoder writes each run into an unbounded `io.BytesIO` and can expand roughly 85x per run: - `src/PIL/MspImagePlugin.py:144-146` ### Impact Memory-exhaustion denial of service from a tiny crafted image in any application that loads pixels. The expansion is decoupled from the declared pixel count, so `MAX_IMAGE_PIXELS` does not bound it.

Check your whole app

Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.

References

Merged from GitHub Advisory Database, OSV. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON

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