How severe is CVE-2026-49860?

CVE-2026-49860 has a CVSS 3.x base score of 5.2, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-49860 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-49860?

CVE-2026-49860 affects Deno. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-49860?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-49860 have an EU (EUVD) identifier?

Yes. CVE-2026-49860 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38542.

When was CVE-2026-49860 published?

CVE-2026-49860 was published on 2026-06-23 and last updated on 2026-06-29.

CVE-2026-49860

CVE-2026-49860 is a medium-severity vulnerability in Deno with a CVSS 3.x base score of 5.2. 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-918.

Key facts

Severity: Medium (CVSS 3.x base score 5.2)
EPSS exploit prediction: 0% (1st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-38542
Weakness: CWE-918
Affected product: Deno
Published: 2026-06-23
Last modified: 2026-06-29

Description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, Deno checked the destination hostname against --deny-net rules but did not re-check the IP addresses that hostname resolved to. An attacker-controlled script could use a specially crafted domain name that passes the hostname check yet resolves to a denied IP, bypassing the network restriction entirely. This vulnerability is fixed in 2.8.1.

Frequently asked questions

What is CVE-2026-49860?: Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, Deno checked the destination hostname against --deny-net rules but did not re-check the IP addresses that hostname resolved to. An attacker-controlled script could use a specially crafted domain name that passes the hostname check yet resolves to a denied IP, bypassing the network restriction entirely. This vulnerability is fixed in 2.8.1.
How severe is CVE-2026-49860?: CVE-2026-49860 has a CVSS 3.x base score of 5.2, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-49860 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-49860?: CVE-2026-49860 affects Deno. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-49860?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-49860 have an EU (EUVD) identifier?: Yes. CVE-2026-49860 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38542.
When was CVE-2026-49860 published?: CVE-2026-49860 was published on 2026-06-23 and last updated on 2026-06-29.

References

https://github.com/denoland/deno/security/advisories/GHSA-83pc-3rw9-qpwj

Affected products (1)

cpe:2.3:a:deno:deno:*:*:*:*:*:*:*:*

More vulnerabilities in Deno

CVE-2022-24783 — Critical (CVSS 10.0): Deno is a runtime for JavaScript and TypeScript. The versions of Deno between release 1.18.0 and 1.20.2 (inclusive) are…
CVE-2023-28445 — Critical (CVSS 9.9): Deno is a runtime for JavaScript and TypeScript that uses V8 and is built in Rust. Resizable ArrayBuffers passed to…
CVE-2021-32619 — Critical (CVSS 9.8): Deno is a runtime for JavaScript and TypeScript that uses V8 and is built in Rust. In Deno versions 1.5.0 to 1.10.1,…
CVE-2025-48935 — Critical (CVSS 9.1): Deno is a JavaScript, TypeScript, and WebAssembly runtime. Starting in version 2.2.0 and prior to versions 2.2.5, it is…
CVE-2024-27936 — High (CVSS 8.8): Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. Starting in version 1.32.1 and prior to…
CVE-2023-28446 — High (CVSS 8.8): Deno is a simple, modern and secure runtime for JavaScript and TypeScript that uses V8 and is built in Rust. Arbitrary…

All CVEs affecting Deno →

Other CWE-918 (Server-Side Request Forgery (SSRF)) vulnerabilities

CVE-2026-47938 — Critical (CVSS 10.0): Adobe Campaign Classic (ACC) versions 7.4.3 build 9394 and earlier are affected by a Server-Side Request Forgery (SSRF)…
CVE-2026-35431 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Microsoft Entra ID Entitlement Management allows an unauthorized attacker to…
CVE-2026-32186 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Microsoft Bing allows an unauthorized attacker to elevate privileges over a…
CVE-2026-33107 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Azure Databricks allows an unauthorized attacker to elevate privileges over a…
CVE-2026-32871 — Critical (CVSS 10.0): FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP…
CVE-2026-32169 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Azure Cloud Shell allows an unauthorized attacker to elevate privileges over a…

Browse all CWE-918 (Server-Side Request Forgery (SSRF)) vulnerabilities →