CVE-2026-49859 json
Deno: `fetch()` API sandbox bypass via missing DNS resolution check
published 2026-06-16 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-38541 , GHSA-cpgj-f7g3-2pp2 , JLSEC-2026-1164
- cvss
- 5.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 3%
- public exploits
- 0
- none known
Summary
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when fetch() was called, 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.
Patch / fix
- crates.io deno 2.8.1
- julia Deno_jll 2.8.1+0
- deno deno 2.8.1
- deno deno_runtime 2.8.1
- deno serde_v8 2.8.1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
| GitHub | 3.1 | 5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
| OSV | 3.1 | 5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | deno | <2.8.1 |
2.8.1 |
| julia | Deno_jll | <2.8.1+0 |
2.8.1+0 |
Affected products
- denoland deno
Classification
References
-
github.com
/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2
web, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-49859
advisory, web
-
github.com
/denoland/deno
package
-
github.com
/advisories/GHSA-cpgj-f7g3-2pp2
web
Sources
- CVE List CVE-2026-49859
- GitHub Advisory GHSA-cpgj-f7g3-2pp2
- NVD CVE-2026-49859
- OSV JLSEC-2026-1164
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.