tesseract-ocr Tesseract up to 5.5.3 Unicharset unicharset.cpp load_via_fgets out-of-bounds write

Summaryinfo

A vulnerability identified as critical has been detected in tesseract-ocr Tesseract up to 5.5.3. This affects the function UNICHARSET::load_via_fgets of the file src/ccutil/unicharset.cpp of the component Unicharset. The manipulation leads to out-of-bounds write. This vulnerability is listed as CVE-2026-88052. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in tesseract-ocr Tesseract up to 5.5.3. It has been rated as critical. This issue affects the function UNICHARSET::load_via_fgets of the file src/ccutil/unicharset.cpp of the component Unicharset. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-88052 since 09/09/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/10/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• tesseract-ocr

Name

• Tesseract

Version

• 5.5.0
• 5.5.1
• 5.5.2
• 5.5.3

Website

• Product: https://github.com/tesseract-ocr/tesseract/

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