# Pillow: Heap buffer overflow in \_tiffWriteProc when saving TIFF to BytesIO

Advisory record · `GHSA-332p-7hrc-92wf`

- **Identifiers:** `GHSA-332p-7hrc-92wf` · `BIT-pillow-2026-112393` · `CVE-2026-112393`
- **State:** Confirmed
- **Severity:** CVSS 9.2 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-122](https://cwe.mitre.org/data/definitions/122.html)
- **Tags:** [Memory corruption](https://agentprime.io/advisories/tag/memory-corruption.md)
- **Published:** 21 Oct 2026
- **Updated:** 26 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 21 Oct 2026, 21:28 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.2: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `pillow` (PyPI): affected `>=2.0.0, <13.0.0`; fixed in `13.0.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Pillow versions from 2.0.0 up to but not including 13.0.0 are affected. When an image is saved as TIFF to an in-memory target such as io.BytesIO, a bug in the libtiff write callback (\_tiffWriteProc) can write past the end of a heap buffer and copy stale heap memory into the output file. An attacker who can supply an image that a service opens and re-saves as TIFF this way can trigger it with default save settings; the source reports a crash and says code execution is not demonstrated. The fixed version is 13.0.0, so upgrade Pillow to 13.0.0 or later.

Written 31 Oct 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 9.2 Critical, CVSS 4.0: `CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.010, the 63rd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:07 UTC: First seen by agentprime
- 31 Oct 2026, 14:07 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-332p-7hrc-92wf)

## Sources

- [GitHub Advisory Database: GHSA-332p-7hrc-92wf](https://github.com/advisories/GHSA-332p-7hrc-92wf)
- [OSV: GHSA-332p-7hrc-92wf](https://osv.dev/vulnerability/GHSA-332p-7hrc-92wf)
- <https://github.com/python-pillow/Pillow/security/advisories/GHSA-332p-7hrc-92wf>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-112393>
- <https://github.com/python-pillow/Pillow/commit/11582e5ffbdceb973d5ee593f3105af5a9852b40>
- <https://github.com/python-pillow/Pillow>
- <https://github.com/python-pillow/Pillow/releases/tag/13.0.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-332p-7hrc-92wf>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-332p-7hrc-92wf/>. Everything for agents: <https://agentprime.io/llms.txt>.