CVE-2021-39247Public exploitNetwork attack vector

Barcode-processing crash via final-character over-read

Published Aug 17, 2021 · Updated Aug 4, 2024

Out-of-bounds read in Zint Barcode Generator before 2.10.0 allows context-dependent attackers to crash barcode processing with crafted Code One data. The is_last_single_ascii function checks that its cursor is at the final character but then reads the next byte, passing an out-of-range value into rs_encode_uint. A victim application must process attacker-controlled Code One input; the demonstrated consequence is an AddressSanitizer-detected abort, with no proven data write.

CVSS severity6.5
Medium
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Zint Barcode Generator before 2.10.0 allows context-dependent attackers to crash barcode processing with crafted Code One data. The is_last_single_ascii function checks that its cursor is at the final character but then reads the next byte, passing an out-of-range value into rs_encode_uint. A victim application must process attacker-controlled Code One input; the demonstrated consequence is an AddressSanitizer-detected abort, with no proven data write.

The record

CVE
CVE-2021-39247
Published
Aug 17, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 17, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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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