# CVE-2026-88050: Tesseract out-of-bounds write in UnicharCompress deserialization

Source: https://junglewise.ai/threats/cve-2026-88050-tesseract-out-of-bounds-write-in-unicharcompress-deserialization  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-10. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-88050 · Severity: medium · CVSS 5.5 · Published 2026-09-10

Tesseract is an open-source optical character recognition (OCR) engine used to extract text from images and scanned documents. A flaw in how it loads trained model files (.traineddata) allows a crafted malicious model file to cause a crash or potentially trigger memory allocation failures, disrupting OCR services that rely on this library.

Technologies: [Tesseract OCR Tesseract](https://junglewise.ai/threats/technologies/tesseract). Vendors: [Tesseract OCR](https://junglewise.ai/threats/vendors/tesseract-ocr).

## Quick answers

**Is CVE-2026-88050 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88050 being exploited in the wild.

**How severe is CVE-2026-88050?** Medium severity, with a CVSS score of 5.5, published 10 September 2026.

**Which products and versions are affected?** Tesseract OCR Tesseract 5.5.3 and earlier.

**Is there a fix for CVE-2026-88050?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-88050 attacked?** It is attacked with local access.

**Am I affected by CVE-2026-88050?** Check whether you run Tesseract OCR Tesseract at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an out-of-bounds write in the UnicharCompress deserialization logic (src/ccutil/unicharcompress.h and .cpp). RecodedCharID::DeSerialize validates the length_ field but fails to validate individual code_[] values, which are read as raw signed int32s. When a negative code value is supplied in a crafted .traineddata recoder component, ComputeCodeRange produces a code_range_ of zero due to improper signed integer comparison. Subsequently, SetupDecoder indexes the is_valid_start_ std::vector<bool> with the negative code on a zero-sized vector, causing an out-of-bounds write at a large wrapped memory address. The attack vector requires loading a malicious .traineddata file; the default LSTM engine is affected. The resulting crash reliably causes a denial of service; no fixed release is available as of the advisory publication date.

## Affected products

- Tesseract OCR Tesseract 5.5.3 and earlier

## Timeline

- 2026-09-10: disclosed
- 2026-08-25: advisory: GitHub Security Advisory GHSA-7v9h-3q3m-w68g published

## References

- [https://github.com/tesseract-ocr/tesseract/commit/c94a5532ee04db5a4919542832fd94caee5ea58f](https://github.com/tesseract-ocr/tesseract/commit/c94a5532ee04db5a4919542832fd94caee5ea58f)
- [https://github.com/tesseract-ocr/tesseract/security/advisories/GHSA-7v9h-3q3m-w68g](https://github.com/tesseract-ocr/tesseract/security/advisories/GHSA-7v9h-3q3m-w68g)

## Related threats

- [Tesseract unsafe pointer deserialization in adaptive templates](https://junglewise.ai/threats/cve-2026-119341-tesseract-is-an-open-source-ocr-engine-prior-to-5-5-4)
- [Tesseract matrix deserialization integer overflow denial of service](https://junglewise.ai/threats/cve-2026-119340-tesseract-is-an-open-source-ocr-engine-prior-to-5-5-4-generic-2d)
- [Tesseract empty network stack denial of service in model deserialization](https://junglewise.ai/threats/cve-2026-88054-tesseract-empty-network-stack-denial-of-service-in-model)
- [Tesseract OCR heap out-of-bounds write in inttemp deserialization](https://junglewise.ai/threats/cve-2026-88053-tesseract-ocr-heap-out-of-bounds-write-in-inttemp-deserialization)
- [Tesseract heap out-of-bounds write in UNICHARSET loading](https://junglewise.ai/threats/cve-2026-88052-tesseract-heap-out-of-bounds-write-in-unicharset-loading)