CVE-2026-88049 Tesseract: Heap out-of-bounds write in LSTM::Forward via na_/gate-matrix dimension mismatch
A heap out-of-bounds write in Tesseract's LSTM engine allows attackers to cause crashes or potentially execute code via crafted traineddata files.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-88049?
CVE-2026-88049 is a high-severity memory corruption vulnerability in tesseract-ocr tesseract, published on 10 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Tesseract is an open source OCR engine. In version 5.5.3 and earlier, prior .traineddata hardening added bounds checks to NetworkIO::CopyTimeStepGeneral and NetworkIO::Randomize in src/lstm/networkio.cpp but left NetworkIO::WriteTimeStepPart and NetworkIO::AddTimeStepPart unchecked. In LSTM::Forward in src/lstm/lstm.cpp, source_ is sized from the independently deserialized na_ field while the WriteTimeStepPart count is ns_, which comes from the CI gate WeightMatrix dim1() value. A crafted NT_LSTM layer can make ns_ much larger than na_, causing a heap out-of-bounds write during the first recognition step on the default LSTM engine and resulting in heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.
Weakness: CWE-787
Which versions are affected by CVE-2026-88049?
It affects 1 product.
Products include Tesseract-Ocr Tesseract Ocr.
How do I fix CVE-2026-88049?
No fix published yet.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-88049 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88049 exists.
Other vulnerabilities in tesseract-ocr tesseract
- CVE-2026-88047 Tesseract: ReadNormProtos stack buffer overflow
- CVE-2026-88048 Tesseract: Heap out-of-bounds write/read in FullyConnected::Forward via layer/weight-matrix dimension mismatch
- CVE-2026-88051 Tesseract: Heap out-of-bounds write in GenericVector<T>::read due to independent reserved/size_used_ fields
- CVE-2026-88053 Tesseract: Heap out-of-bounds write in Classify::ReadIntTemplates via unvalidated counts in crafted .traineddata
- CVE-2026-88052 Tesseract: Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization
Sources
Also known as DEBIAN-CVE-2026-88049, ECHO-7334-3526-1631, GHSA-jgq8-pprg-vc68, UBUNTU-CVE-2026-88049.