How severe is CVE-2021-26233?

CVE-2021-26233 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-26233 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26233?

CVE-2021-26233 affects Faststone Image Viewer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-26233?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-26233 published?

CVE-2021-26233 was published on 2021-03-18 and last updated on 2026-06-17.

CVE-2021-26233

CVE-2021-26233 is a high-severity vulnerability in Faststone Image Viewer with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 6.8
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Faststone Image Viewer
Published: 2021-03-18
Last modified: 2026-06-17

Description

FastStone Image Viewer <= 7.5 is affected by a user mode write access violation near NULL at 0x005bdfcb, triggered when a user opens or views a malformed CUR file that is mishandled by FSViewer.exe. Attackers could exploit this issue for a Denial of Service (DoS) or possibly to achieve code execution.

Frequently asked questions

What is CVE-2021-26233?: FastStone Image Viewer <= 7.5 is affected by a user mode write access violation near NULL at 0x005bdfcb, triggered when a user opens or views a malformed CUR file that is mishandled by FSViewer.exe. Attackers could exploit this issue for a Denial of Service (DoS) or possibly to achieve code execution.
How severe is CVE-2021-26233?: CVE-2021-26233 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-26233 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26233?: CVE-2021-26233 affects Faststone Image Viewer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-26233?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-26233 published?: CVE-2021-26233 was published on 2021-03-18 and last updated on 2026-06-17.

References

https://voidsec.com/advisories/cve-2021-26233-faststone-image-viewer-v-7-5-user-mode-write-access-violation/

Affected products (1)

cpe:2.3:a:faststone:image_viewer:*:*:*:*:*:*:*:*

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