Tesseract: Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization (CVE-2026-88052) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-88052

Tesseract: Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization

Answer in brief

CVE-2026-88052 records a Unknown severity vulnerability in Tesseract: Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization. The current sources do not mark it as known exploited. The current feed maps tesseract-ocr/tesseract (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 10, 2026Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps tesseract-ocr/tesseract (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
tesseract-ocr/tesseractgeneric	<= 5.5.3	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for tesseract-ocr/tesseract.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, UNICHARSET::load_via_fgets in src/ccutil/unicharset.cpp trusts the declared unichar count as a loop bound and uses id as an unchecked index into the unichars vector. unichar_insert_backwards_compatible can leave the vector unchanged for an empty, duplicate, or already-encodable representation, causing id to become larger than unichars.size(). Subsequent set_* calls and the write to unichars[id].properties.enabled then write UNICHAR_PROPERTIES beyond the vector during initialization in both the default LSTM and legacy engines, causing heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

Quoted source text, attributed separately from HOL analysis.