How severe is CVE-2026-54321?

CVE-2026-54321 has a CVSS score of 7/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-54321?

CVE-2026-54321 affects the following packages: github.com/daytonaio/daytona (Go). Ecosystems affected: Go.

How do I fix CVE-2026-54321?

Update github.com/daytonaio/daytona to 0.184.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54321 is resolved across your whole dependency graph.

How do I detect CVE-2026-54321 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/daytonaio/daytona, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-54321 if there is no patch (or I can't update yet)?

Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Is CVE-2026-54321 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-54321 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-54321?

CVE-2026-54321 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 31th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-54321?

CVE-2026-54321 is classified as CWE-613 (CWE-613), CWE-863 (CWE-863). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-54321 published, and has it been updated?

CVE-2026-54321 was published on June 23, 2026 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2026-54321 — daytona

HIGH

CVE-2026-54321 is a high-severity (CVSS 7) CWE-613 vulnerability in github.com/daytonaio/daytona. A fix is available for github.com/daytonaio/daytona — see the affected versions and patch details below.

Daytona: Public sandbox previews remain accessible for up to one hour after being made private

Also known asGHSA-ww63-pv5x-vfc8GO-2026-5729

Published

Jun 23, 2026

Updated

Aug 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54321.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs31th percentile — riskier than 31% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-54321 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐹github.com/daytonaio/daytona

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Sandbox previews that were switched from public to private could remain reachable without authentication for a short period after the change, due to a cached visibility state that was not invalidated when the sandbox's visibility changed.

Impact

When a sandbox owner changed a preview from public to private, the preview proxy could continue serving unauthenticated requests to that sandbox's ordinary preview ports for a bounded period before the change took effect. Only sandboxes that had been made public and were later set back to private were affected, and only until the proxy's cached visibility state was refreshed. Terminal, toolbox, and recording-dashboard ports were never affected, as those always require authentication. The issue did not involve cross-tenant access, privilege escalation, or remote code execution.

Patches

Fixed in v0.184.0. Sandbox visibility changes now invalidate the proxy's cached preview state immediately, so revoking a public preview takes effect on the next request.

Workarounds

Upgrade to v0.184.0 or later. There is no configuration workaround for earlier versions.

Credit

Reported through Daytona's Vulnerability Disclosure Program by mrknightnidu(nidalkhan). Linkedin: https://www.linkedin.com/in/mrknight-nidu-031340328/

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/daytonaio/daytona`	≥ 0.101.0&&< 0.184.0	0.184.0`go get github.com/daytonaio/daytona@v0.184.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/daytonaio/daytona, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/daytonaio/daytona to 0.184.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54321 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Frequently Asked Questions

### Summary Sandbox previews that were switched from public to private could remain reachable without authentication for a short period after the change, due to a cached visibility state that was not invalidated when the sandbox's visibility changed. ### Impact When a sandbox owner changed a preview from public to private, the preview proxy could continue serving unauthenticated requests to that sandbox's ordinary preview ports for a bounded period before the change took effect. Only sandboxes that had been made public and were later set back to private were affected, and only until the proxy