EUVD-2026-75629Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local attack vector because exploitation requires loading a crafted file into the process; UI:R because the file must be processed by a user or pipeline action; PR:N since no authenticated session is needed to supply the file.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
4DescriptionCVE.org
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.
AnalysisAI
Heap corruption in Tesseract OCR 5.5.3 and earlier allows an attacker who can supply a malicious unicharset file to corrupt application heap memory during OCR engine initialization, potentially leading to a crash or controlled code execution. The root cause is that UNICHARSET::load_via_fgets treats the declared character count as a trusted loop bound and uses the incrementing id variable as a direct unichars vector index, while unichar_insert_backwards_compatible silently performs no-op insertions for duplicate or empty representations - causing id to exceed unichars.size() and subsequent set_* writes to access memory beyond the vector. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a Tesseract process to call load_via_fgets on an attacker-controlled unicharset file containing either a duplicate character representation (same glyph appearing more than once), an empty representation, or an already-encodable representation that causes unichar_insert_backwards_compatible to perform a no-op insertion. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.8 score with AV:L/AC:L/PR:N/UI:R accurately characterizes this as a client-side file-processing vulnerability; exploitation requires a Tesseract process to actually load a crafted unicharset file, either via direct user invocation or an automated document-processing pipeline. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | No vendor-released patched version is available as of this review; the upstream fix exists only as source commit 2d04d640db2e8c7e3bab2369d599343b5a8b8443 on GitHub. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory all systems running Tesseract OCR and identify which versions are deployed, with particular focus on any systems processing external or user-supplied documents. …
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Same weakness CWE-129 – Improper Validation of Array Index
View allSame technique Denial Of Service
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External POC / Exploit Code
Leaving vuln.today