How severe is CVE-2021-26235?

CVE-2021-26235 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-2021-26235 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-2021-26235?

CVE-2021-26235 affects Faststone Image Viewer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-26235?

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-2021-26235 published?

CVE-2021-26235 was published on 2021-03-18 and last updated on 2026-06-17.

CVE-2021-26235

CVE-2021-26235 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-476.

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-476
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 0x005bdfc9, 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-2021-26235?: FastStone Image Viewer <= 7.5 is affected by a user mode write access violation near NULL at 0x005bdfc9, 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-2021-26235?: CVE-2021-26235 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-2021-26235 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-2021-26235?: CVE-2021-26235 affects Faststone Image Viewer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-26235?: 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-2021-26235 published?: CVE-2021-26235 was published on 2021-03-18 and last updated on 2026-06-17.

References

https://voidsec.com/advisories/cve-2021-26235-faststone-image-viewer-v-7-5-user-mode-write-access-violation/

Affected products (1)

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

More vulnerabilities in Faststone Image Viewer

CVE-2022-36947 — Critical (CVSS 9.8): Unsafe Parsing of a PNG tRNS chunk in FastStone Image Viewer through 7.5 results in a stack buffer overflow.
CVE-2007-1942 — Critical (CVSS 9.3): Integer overflow in FastStone Image Viewer 2.9 allows context-dependent attackers to cause a denial of service and…
CVE-2024-9114 — High (CVSS 7.8): FastStone Image Viewer GIF File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability…
CVE-2024-9113 — High (CVSS 7.8): FastStone Image Viewer TGA File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability…
CVE-2024-9112 — High (CVSS 7.8): FastStone Image Viewer PSD File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability…
CVE-2021-26237 — High (CVSS 7.8): FastStone Image Viewer <= 7.5 is affected by a user mode write access violation at 0x00402d7d, triggered when a user…

All CVEs affecting Faststone Image Viewer →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

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CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

Browse all CWE-476 (NULL Pointer Dereference) vulnerabilities →