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Response snapshot Oct 26, 2026, 22:42 UTC

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VulnerabilityCVE-2026-16477

CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations).

CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). Exploitation requires an attacker to craft a malicious .

At a glance

Exploited
Not known
Severity
8.4 High (CVSS 4.0)
Chance of exploitation
0.3% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-16477 (opens a new tab)

What happened

CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). Exploitation requires an attacker to craft a malicious .cleanshot file, deliver it to the target, and have the target open it; the payload then executes automatically during parsing, resulting in arbitrary code execution in the context of the current user.

Users who have never opened a .cleanshot file from an untrusted source are not affected by this vulnerability. This vulnerability was fixed in versions: 4.5.2, 4.6.3, 4.7.8 and 4.8.10

Scores and how they were measured

CVSS base severity

8.4

Version 4.0As of

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.3%

Scored Percentile 21.1%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-16477 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-16477, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 22). CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). (CVE-2026-16477). https://kevwire.com/record/CVE-2026-16477

MLA

"CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). (CVE-2026-16477)." KEVWire, 22 Oct. 2026, kevwire.com/record/CVE-2026-16477.

Chicago

KEVWire. "CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). (CVE-2026-16477)." Last modified October 22, 2026. https://kevwire.com/record/CVE-2026-16477.

Evidence summary (plain text)

CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). (Oct 22, 2026).
CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). Exploitation requires an attacker to craft a malicious .cleanshot file, deliver it to the target, and have the target open it; the payload then executes automatically during parsing, resulting in arbitrary code execution in the context of the current user. Users who have never opened a .cleanshot file from an untrusted source are not affected by this vulnerability. This vulnerability was fixed in versions: 4.5.2, 4.6.3, 4.7.8 and 4.8.10
CVSS 8.4 (version 4.0; evidence as of Oct 22, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-16477).
EPSS 0.3% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-16477&date=2026-10-26).
Sources:
NVD CVE-2026-16477: https://nvd.nist.gov/vuln/detail/CVE-2026-16477
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=8500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-16477&date=2026-10-26
Record ID: CVE-2026-16477.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Awaiting Analysis. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

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Record details

Record detail