CVE-2026-49860Deno: WebSocket API sandbox bypass via missing post-DNS check
- 5.2MediumCVSS base score
- 0.14%Exploitation in 30 daysEPSS · top 97% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 22 days later
· 22 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
| NVDNVD · Analyzed | 3.1 | Medium5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
- EPSS (exploitation in 30 days)
- 0.14% · top 97% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.2.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- crates.iodenoGHSA-83pc-3rw9-qpwj (opens in a new tab)
References
References1
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-38542 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-83pc-3rw9-qpwj (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-49860)Record last updated .