Vulnerability · Published Sep 10, 2026 · Assigned by GitHub_M
CVE-2026-88052Tesseract: Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization
High 7.8
In plain English
A high-severity out-of-bounds write in tesseract from tesseract-ocr. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | tesseract | 5.3.4-11.el10_2 | ALSA-2026:95085 |
| AlmaLinux:8 | tesseract | 4.1.1-7.el8_10 | ALSA-2026:95725 |
| AlmaLinux:10 | tesseract-devel | 5.3.4-11.el10_2 | ALSA-2026:95085 |
| AlmaLinux:8 | tesseract-devel | 4.1.1-7.el8_10 | ALSA-2026:95725 |
| AlmaLinux:9 | tesseract-devel | 4.1.1-11.el9_8 | ALSA-2026:95086 |
| Debian:12 | tesseract | no fix listed | DEBIAN-CVE-2026-88052 |
| Debian:13 | tesseract | no fix listed | DEBIAN-CVE-2026-88052 |
| Debian:14 | tesseract | no fix listed | DEBIAN-CVE-2026-88052 |
| Rocky Linux:10 | tesseract | 0:5.3.4-11.el10_2 | RLSA-2026:95085 |
| Rocky Linux:9 | tesseract | 0:4.1.1-11.el9_8 | RLSA-2026:95086 |
| Ubuntu:26.10 | tesseract | no fix listed | UBUNTU-CVE-2026-88052 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| tesseract-ocr | tesseract | <= 5.5.3 |
Weakness: CWE-129, CWE-787 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H