Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 0.18% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-88052High confidence
Tesseract: Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization
tesseract-ocr · tesseract
Official source article: GitHub GHSA-2HM8-Q5C7-C373 ↗. Check the applicable product and release in the original source.
7.8HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh 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 210 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
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
- Confirm that the asset runs tesseract-ocr tesseract and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 210 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 206 affected or under-investigation product states without a fixed product state in the same current advisory
- Debian Security Tracker: 4 affected package states with no published fix
Distribution package intelligence
5 package statesRelease-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.
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 release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | tesseract | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Debian bookwormbookworm · source | tesseract | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Debian forkyforky · source | tesseract | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Debian sidsid · source | tesseract | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Ubuntu 24.04 LTSnoble · esm-apps | tesseract | Vendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree. | 5.3.4-1ubuntu0.1~esm1 | Canonical Ubuntu Security ↗Source updated 7 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative 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.
CVE-2026-88052 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitytesseract: Tesseract: Heap out-of-bounds write can lead to arbitrary code execution
The vendor explicitly identifies these products as affected by this CVE.
- 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
- Summary
- A flaw was found in Tesseract, an open-source Optical Character Recognition (OCR) engine. The UNICHARSET::load_via_fgets function incorrectly trusts a declared character count, which can lead to an out-of-bounds write in memory. A remote attacker could exploit this vulnerability by providing a specially crafted input, potentially causing heap corruption, a denial of service, or arbitrary code execution.
- Remediation
- To mitigate this vulnerability, avoid processing untrusted or malicious image and document files with Tesseract. If Tesseract is not essential for system operations, consider removing the `tesseract` package to eliminate the attack surface. If the `tesseract` package is removed, ensure that any dependent applications or services are not adversely affected.
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 210 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
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.
What
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.
Why
The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
How
An attacker operating through local access may attempt exploitation without authentication after a 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, 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.
Why
The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
How
An attacker operating through local access may attempt exploitation without authentication after a 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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 → Improper Validation of Array Index → disrupt the affected service
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Required interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-129 ↗
CWE-129: Improper Validation of Array Index. The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: 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.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- 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.
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
- 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
- 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 vulnerability, avoid processing untrusted or malicious image and document files with Tesseract. If Tesseract is not essential for system operations, consider removing the `tesseract` package to eliminate the attack surface. If the `tesseract` package is removed, ensure that any dependent applications or services are not adversely affected.
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.
- Heap out-of-bounds write in UNICHARSET::load_via_fgets via count/insert desynchronization · Advisory · tesseract-ocr/tesseract · GitHub →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026tesseract-ocr / tesseract Public Notifications You must be signed in to change notification settings Fork 10.8k Star 76.7k Code Issues 437 Pull requests 50 Actions Projects Wiki Security and quality 10 Insights Additional navigation options Code Issues Pull requests Actions Projects Wiki Security and
04
Evidence and provenance
Published 10 Sept 2026 · Last source change 11 Sept 2026, 20:33 UTC · CWE-129 · Improper Validation of Array Index
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-11
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-75629
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
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed: added mitigation: github.com/GHSA-2hm8-q5c7-c373; added patch: github.com/2d04d640db2e8c7e3bab2369d599343b5a8b8443; 1 further additions.security-advisories@github.com ↗
- Before
- no authoritative guidance recorded
- After
- mitigation: github.com/GHSA-2hm8-q5c7-c373 · patch: github.com/2d04d640db2e8c7e3bab2369d599343b5a8b8443 · remediation: github.com/2d04d640db2e8c7e3bab2369d599343b5a8b8443
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- 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.
- Remediation statusRemediation status changed from Awaiting fix to Patch available.security-advisories@github.com ↗
- Before
- Awaiting fix
- After
- Patch available
- Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.security-advisories@github.com ↗
- Before
- No public exploit
- After
- Public exploit reference
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- 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.
- ENISA EUVD mappingEUVD-2026-75629 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-75629"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
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.