CVE-2021-36081

Application crash via freed heap read

Published Jul 1, 2021 · Updated Aug 4, 2024

Use-after-free in Tesseract OCR 5.0.0-alpha-20201231 allows local users to crash applications that process crafted image input. Within one_ell_conflict, strpbrk reads two bytes from released heap memory after the referenced allocation has been freed. Exploitation requires an application to process attacker-controlled OCR input; public OSS-Fuzz evidence demonstrates a memory-safety crash, not controlled code execution.

CVSS severity7.8
High
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Tesseract OCR 5.0.0-alpha-20201231 allows local users to crash applications that process crafted image input. Within one_ell_conflict, strpbrk reads two bytes from released heap memory after the referenced allocation has been freed. Exploitation requires an application to process attacker-controlled OCR input; public OSS-Fuzz evidence demonstrates a memory-safety crash, not controlled code execution.

The record

CVE
CVE-2021-36081
Published
Jul 1, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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