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Full vulnerability report · 2026
CVE-2026-88051High confidence

Tesseract: Heap out-of-bounds write in GenericVector<T>::read due to independent reserved/size_used_ fields

tesseract-ocr · tesseract

Official source article: GitHub GHSA-88QP-4G94-3RF3 ↗. Check the applicable product and release in the original source.

8.6HighCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 13 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 0.17% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs tesseract-ocr tesseract and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 13 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 4 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcetesseractAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcetesseractAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcetesseractAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcetesseractAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivetesseractUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-88051 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitytesseract: Tesseract: Heap out-of-bounds write via crafted .traineddata model
9 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • tesseract as a component of Red Hat Enterprise Linux 10
  • tesseract-devel as a component of Red Hat Enterprise Linux 10
  • tesseract.src as a component of Red Hat Enterprise Linux 10
  • tesseract as a component of Red Hat Enterprise Linux 8
  • tesseract-devel as a component of Red Hat Enterprise Linux 8
  • tesseract.src as a component of Red Hat Enterprise Linux 8
  • tesseract as a component of Red Hat Enterprise Linux 9
  • tesseract-devel as a component of Red Hat Enterprise Linux 9
  • tesseract.src as a component of Red Hat Enterprise Linux 9
Summary
A flaw was found in Tesseract, an open-source Optical Character Recognition (OCR) engine. A heap out-of-bounds write vulnerability exists in the GenericVector::read function when processing a specially crafted .traineddata model. By manipulating the reserved and size_used_ fields, a local attacker can cause heap corruption, a crash, or potentially controlled corruption, which could lead to arbitrary code execution.
Remediation
To mitigate this issue, avoid processing `.traineddata` model files from untrusted or unknown sources. Ensure that Tesseract only processes models from trusted origins. If Tesseract is not required, consider removing the `tesseract` package to eliminate the attack surface.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-75627

No EUVD known-exploited evidence

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, the callback form of GenericVector::read in src/ccutil/genericvector.h reads the independent int32 fields reserved and size_used_ from a .traineddata model without a cap or an invariant check. reserve(reserved) allocates the backing array, but the callback loop writes size_used_ elements. A crafted TESSDATA_INTTEMP component with version_id 4 or later can therefore set reserved to a small value and size_used_ to a large value when fontinfo_table_.read(fp, read_info) is called from src/classify/intproto.cpp, causing a heap out-of-bounds write of FontInfo structures, heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
8.6 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 13 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, the callback form of GenericVector::read in src/ccutil/genericvector.h reads the independent int32 fields reserved and size_used_ from a .traineddata model without a cap or an invariant check. reserve(reserved) allocates the backing array, but the callback loop writes size_used_ elements. A crafted TESSDATA_INTTEMP component with version_id 4 or later can therefore set reserved to a small value and size_used_ to a large value when fontinfo_table_.read(fp, read_info) is called from src/classify/intproto.cpp, causing a heap out-of-bounds write of FontInfo structures, heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

What

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, the callback form of GenericVector::read in src/ccutil/genericvector.h reads the independent int32 fields reserved and size_used_ from a .traineddata model without a cap or an invariant check. reserve(reserved) allocates the backing array, but the callback loop writes size_used_ elements. A crafted TESSDATA_INTTEMP component with version_id 4 or later can therefore set reserved to a small value and size_used_ to a large value when fontinfo_table_.read(fp, read_info) is called from src/classify/intproto.cpp, causing a heap out-of-bounds write of FontInfo structures, heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, the callback form of GenericVector::read in src/ccutil/genericvector.h reads the independent int32 fields reserved and size_used_ from a .traineddata model without a cap or an invariant check. reserve(reserved) allocates the backing array, but the callback loop writes size_used_ elements. A crafted TESSDATA_INTTEMP component with version_id 4 or later can therefore set reserved to a small value and size_used_ to a large value when fontinfo_table_.read(fp, read_info) is called from src/classify/intproto.cpp, causing a heap out-of-bounds write of FontInfo structures, heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
local access → Out-of-bounds Write → disrupt the affected service
Attack surface
Local
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-787 ↗

CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedDenial of serviceCWE-787Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-75627Official EUVD mapping

Tesseract is an open source OCR engine. In version 5.5.3 and earlier, the callback form of GenericVector::read in src/ccutil/genericvector.h reads the independent int32 fields reserved and size_used_ from a .traineddata model without a cap or an invariant check. reserve(reserved) allocates the backing array, but the callback loop writes size_used_ elements. A crafted TESSDATA_INTTEMP component with version_id 4 or later can therefore set reserved to a small value and size_used_ to a large value when fontinfo_table_.read(fp, read_info) is called from src/classify/intproto.cpp, causing a heap out-of-bounds write of FontInfo structures, heap corruption, a crash, or potentially controlled corruption. No fixed release is available as of this review.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260916Security Bulletin 16 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 16 Sep 2026, published on 16 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-034173Tesseract OCRにおける境界外書き込みに関する脆弱性

TesseractはオープンソースのOCRエンジンです。バージョン5.5.3およびそれ以前のバージョンでは、src/ccutil/genericvector.h内のGenericVector::readのコールバック形式において、独立したint32型フィールドであるreservedとsize_used_を.traineddataモデルから制限や不変条件のチェックなしに読み取っていました。reserve(reserved)は内部配列を確保しますが、コールバックループはsize_used_要素を書き込みます。したがって、バージョンIDが4以上のTESSDATA_INTTEMPコンポーネントを細工すると、src/classify/intproto.cpp内のfontinfo_table_.read(fp, read_info)呼び出し時にreservedを小さな値に、size_used_を大きな値に設定でき、その結果フォント情報(FontInfo)構造体にヒープの境界外書き込みが発生し、ヒープ破損やクラッシュ、または潜在的に制御可能な破損を引き起こす可能性があります。この問題について、レビュー時点では修正されたリリースはまだ提供されていません。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
To mitigate this issue, avoid processing `.traineddata` model files from untrusted or unknown sources. Ensure that Tesseract only processes models from trusted origins. If Tesseract is not required, consider removing the `tesseract` package to eliminate the attack surface.
Official vendor articles1 stored document

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

04

Evidence and provenance

Published 10 Sept 2026 · Last source change 15 Sept 2026, 14:53 UTC · CWE-787 · Out-of-bounds Write

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-11
European sourceENISA EUVD · EUVD-2026-75627
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    tesseract-devel as a component of Red Hat Enterprise Linux 10; tesseract-langpack-afr as a component of Red Hat Enterprise Linux 10; tesseract-langpack-amh as a component of Red Hat Enterprise Linux 10; tesseract-langpack-ara as a component of Red Hat Enterprise Linux 10; tesseract-langpack-asm as a component of Red Hat Enterprise Linux 10; tesseract-langpack-aze as a component of Red Hat Enterprise Linux 10; tesseract-langpack-aze_cyrl as a component of Red Hat Enterprise Linux 10; tesseract-langpack-bel as a component of Red Hat Enterprise Linux 10; tesseract-langpack-ben as a component of Red Hat Enterprise Linux 10; tesseract-langpack-bod as a component of Red Hat Enterprise Linux 10; tesseract-langpack-bos as a component of Red Hat Enterprise Linux 10; tesseract-langpack-bul as a component of Red Hat Enterprise Linux 10; tesseract-langpack-cat as a component of Red Hat Enterprise Linux 10; tesseract-langpack-ceb as a component of Red Hat Enterprise Linux 10; tesseract-langpack-ces as a component of Red Hat Enterprise Linux 10; tesseract-langpack-chi_sim as a component of Red Hat Enterprise Linux 10; tesseract-langpack-chi_tra as a component of Red Hat Enterprise Linux 10; tesseract-langpack-chr as a component of Red Hat Enterprise Linux 10; tesseract-langpack-cym as a component of Red Hat Enterprise Linux 10; tesseract-langpack-dan as a component of Red Hat Enterprise Linux 10; tesseract-langpack-deu as a component of Red Hat Enterprise Linux 10; tesseract-langpack-dzo as a component of Red Hat Enterprise Linux 10; tesseract-langpack-ell as a component of Red Hat Enterprise Linux 10; tesseract-langpack-enm as a component of Red Hat Enterprise Linux 10; tesseract-langpack-epo as a component of Red Hat Enterprise Linux 10; tesseract-langpack-est as a component of Red Hat Enterprise Linux 10; tesseract-langpack-eus as a component of Red Hat Enterprise Linux 10; tesseract-langpack-fas as a component of Red Hat Enterprise Linux 10; tesseract-langpack-fin as a component of Red Hat Enterprise Linux 10; tesseract-langpack-fra as a component of Red Hat Enterprise Linux 10; and 176 more
    After
    tesseract as a component of Red Hat Enterprise Linux 10; tesseract-devel as a component of Red Hat Enterprise Linux 10; tesseract.src as a component of Red Hat Enterprise Linux 10; tesseract as a component of Red Hat Enterprise Linux 8; tesseract-devel as a component of Red Hat Enterprise Linux 8; tesseract.src as a component of Red Hat Enterprise Linux 8; tesseract as a component of Red Hat Enterprise Linux 9; tesseract-devel as a component of Red Hat Enterprise Linux 9; tesseract.src as a component of Red Hat Enterprise Linux 9
    Red Hat Product Security ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added mitigation: github.com/GHSA-88qp-4g94-3rf3; added patch: github.com/56e09ca12e751623fe796ce1554ce704bffd2ef0; 1 further additions.
    Before
    no authoritative guidance recorded
    After
    mitigation: github.com/GHSA-88qp-4g94-3rf3 · patch: github.com/56e09ca12e751623fe796ce1554ce704bffd2ef0 · remediation: github.com/56e09ca12e751623fe796ce1554ce704bffd2ef0
    github.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    tesseract: <= 5.5.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    tesseract: <= 5.5.3 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    github.com ↗
  5. Public exploit evidencePublic exploit evidence changed from Public exploit reference to Public exploit reference.
    Before
    Public exploit reference
    After
    Public exploit reference
    github.com ↗
  6. Affected versionsThe structured affected or fixed version information changed.
    Before
    <= 5.5.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    tesseract: <= 5.5.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  7. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  8. ENISA EUVD mappingEUVD-2026-75627 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-75627"}
    ENISA EUVD ↗
  9. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-75627↗Vendor CSAF · Red Hat Product Security↗CISA Vulnrichment SSVC evidence↗Public exploit reference · GitHub GHSA-88QP-4G94-3RF3↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-88051 · cve.blacktree.nl