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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tesseract-ocr | tesseract | <= 5.5.3 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | tesseract | No fix yet | — |
| Debian 13 | tesseract | No fix yet | — |
| Debian 12 | tesseract | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | tesseract | No fix yet | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | tesseract | 5.5.0-1ubuntu0.1~esm1 | USN-8882-1 |
| Ubuntu Pro 24.04 LTS | tesseract | 5.3.4-1ubuntu0.1~esm1 | USN-8882-1 |
| Ubuntu Pro 22.04 LTS | tesseract | 4.1.1-2.1ubuntu0.1~esm1 | USN-8882-1 |
| Ubuntu Pro 20.04 LTS | tesseract | 4.1.1-2ubuntu0.1~esm1 | USN-8882-1 |
| Ubuntu Pro 18.04 LTS | tesseract | 4.00~git2288-10f4998a-2ubuntu0.1~esm1 | USN-8882-1 |
| Ubuntu Pro 16.04 LTS | tesseract | 3.04.01-4ubuntu0.1~esm1 | USN-8882-1 |
| Ubuntu Pro 14.04 LTS | tesseract | 3.03.02-3ubuntu0.1~esm1 | USN-8882-1 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | tesseract +1 | 5.3.4-11.el10_2 | ALSA-2026:95085 |
| AlmaLinux 9 | tesseract-devel | 4.1.1-11.el9_8 | ALSA-2026:95086 |
| AlmaLinux 8 | tesseract +1 | 4.1.1-7.el8_10 | ALSA-2026:95725 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | tesseract +1 | 5.3.4-11.el10_2 | RLSA-2026:98624, RLSA-2026:95085 |
| Rocky Linux 9 | tesseract | 4.1.1-11.el9_8 | RLSA-2026:98514, RLSA-2026:95086 |
| Rocky Linux 8 | tesseract | 4.1.1-7.el8_10 | RLSA-2026:95725 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | tesseract-ocr | 5.5.3-2.1 | openSUSE-SU-2026:11887-1 |
| openSUSE Leap 16.0 | tesseract-ocr | 5.5.3-bp160.1.1 | openSUSE-SU-2026:21957-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | tesseract +1 | 5.3.4-11.el10_2 | ELSA-2026-95085 |
| Oracle Linux 9 | tesseract +1 | 4.1.1-11.el9_8 | ELSA-2026-95086 |
| Oracle Linux 8 | tesseract +1 | 4.1.1-7.el8_10 | ELSA-2026-95725 |
Advisories 15
- RLSA-2026:98624 Important: tesseract security update Rocky Linux Security Advisories · Nov 13, 2026
- WID-SEC-2026-4345 Red Hat Enterprise Linux (tesseract): Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- RLSA-2026:98514 Important: tesseract security update Rocky Linux Security Advisories · Nov 12, 2026
- RLSA-2026:95725 Important: tesseract security update Rocky Linux Security Advisories · Nov 7, 2026
- RLSA-2026:95086 Important: tesseract security update Rocky Linux Security Advisories · Nov 6, 2026
- ALSA-2026:95725 Important: tesseract security update AlmaLinux Security Advisories · Nov 6, 2026
- ALSA-2026:95085 Important: tesseract security update AlmaLinux Security Advisories · Nov 5, 2026
- RLSA-2026:95085 Important: tesseract security update Rocky Linux Security Advisories · Nov 5, 2026
- ALSA-2026:95086 Important: tesseract security update AlmaLinux Security Advisories · Nov 5, 2026
- ELSA-2026-95725 Important: tesseract security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Nov 5, 2026
- ELSA-2026-95085 Important: tesseract security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Nov 4, 2026
- ELSA-2026-95086 Important: tesseract security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Nov 4, 2026
- USN-8882-1 tesseract vulnerabilities Ubuntu Security Notices (USN) · Oct 6, 2026
- openSUSE-SU-2026:11887-1 libtesseract5-5.5.3-2.1 on GA media SUSE / openSUSE Security Updates · Sep 25, 2026
- openSUSE-SU-2026:21957-1 Security update for tesseract-ocr SUSE / openSUSE Security Updates · Sep 25, 2026