CVE-2021-26235Public exploit

Application crash via malformed CUR file parsing

Published Mar 18, 2021 · Updated Aug 3, 2024

Memory corruption in FastStone Image Viewer 7.5 and earlier allows local users to crash FSViewer.exe by opening a malformed CUR file. The CUR parser mishandles crafted file data and performs a user-mode write near NULL at address 0x005bdfc9. Exploitation requires a user to open or view the file; the documented result is an FSViewer.exe crash, while code execution remains unverified.

CVSS severity7.8
High
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in FastStone Image Viewer 7.5 and earlier allows local users to crash FSViewer.exe by opening a malformed CUR file. The CUR parser mishandles crafted file data and performs a user-mode write near NULL at address 0x005bdfc9. Exploitation requires a user to open or view the file; the documented result is an FSViewer.exe crash, while code execution remains unverified.

The record

CVE
CVE-2021-26235
Published
Mar 18, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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

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

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1204.002User Execution: Malicious File

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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