CVE-2026-49859

MEDIUMPre-NVD 5.25.2—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 99% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.2
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.2Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.2
EG Score
5.2(medium)
EPSS
1.1%
KEV
Not listed

Published

June 16, 2026

Last Modified

June 29, 2026

Advisory Details (1)

Auto-updated Jun 23, 2026
Patch available. Sources: github.
github Patch Available

`fetch()` API sandbox bypass via missing DNS resolution check · Advisory · denoland/deno · GitHub

https://github.com/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2

Vendor Advisories for CVE-2026-49859(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
crates.io(1)
PackageVulnerable rangeFixed inDependents
deno—2.8.1—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 33× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-06 23:09 UTCEG score recompute
  2. 2026-07-06 02:23 UTCEPSS rescore
  3. 2026-07-05 12:58 UTCEG score recompute
  4. 2026-07-04 13:20 UTCEG score recompute
  5. 2026-07-04 06:31 UTCEPSS rescore
  6. 2026-07-03 13:47 UTCEG score recompute
  7. 2026-07-02 12:53 UTCEG score recompute
  8. 2026-07-01 15:07 UTCEPSS rescore
  9. 2026-07-01 13:20 UTCEG score recompute
  10. 2026-06-30 23:22 UTCEPSS rescore
  11. 2026-06-30 13:41 UTCEG score recompute
  12. 2026-06-29 14:08 UTCEG score recompute
  13. 2026-06-29 14:06 UTCEPSS rescore
  14. 2026-06-29 14:06 UTCEPSS rescore
  15. 2026-06-28 14:35 UTCEG score recompute
  16. 2026-06-28 14:07 UTCEPSS rescore
  17. 2026-06-28 04:56 UTCEPSS rescore
  18. 2026-06-28 04:56 UTCEPSS rescore
  19. 2026-06-27 15:02 UTCEG score recompute
  20. 2026-06-27 03:08 UTCEPSS rescore
  21. 2026-06-26 15:28 UTCEG score recompute
  22. 2026-06-25 15:55 UTCEG score recompute
  23. 2026-06-25 13:49 UTCEPSS rescore
  24. 2026-06-24 16:13 UTCEG score recompute
  25. 2026-06-24 14:05 UTCEPSS rescore
Show 8 more
  1. 2026-06-23 16:38 UTCEG score recompute
  2. 2026-06-22 17:02 UTCEG score recompute
  3. 2026-06-21 17:17 UTCEG score recompute
  4. 2026-06-20 17:32 UTCEG score recompute
  5. 2026-06-19 17:57 UTCEG score recompute
  6. 2026-06-18 18:14 UTCEG score recompute
  7. 2026-06-17 18:39 UTCEG score recompute
  8. 2026-06-16 19:06 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-49859?
CVE-2026-49859 is a medium vulnerability published on June 16, 2026. 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…
When was CVE-2026-49859 disclosed?
CVE-2026-49859 was first published in the National Vulnerability Database on June 16, 2026, with the most recent update on June 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49859 actively exploited?
CVE-2026-49859 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-49859?
CVE-2026-49859 has a CVSS v3 base score of 5.2 (NVD).
How do I remediate CVE-2026-49859?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-49859, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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