CVE-2026-110240: Lancet through 2.3.9 SSRF Protection Bypass via netutil.IsInternalIP

Severity: medium (CVSS 4.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-13
Weakness: CWE-918

Description

Lancet through 2.3.9 contains an SSRF protection bypass vulnerability in netutil.IsInternalIP that misclassifies IPv6 private, link-local, CGNAT and transition addresses as external. Attackers can supply hostnames resolving to these address forms, including NAT64, 6to4 or Teredo embedding internal IPv4, to reach internal services or cloud metadata endpoints.

Affected products

duke-git lancet: from 2.1.2 through 2.3.9; from 1.3.1 through 1.4.6

References

https://github.com/duke-git/lancet
https://github.com/duke-git/lancet/blob/v1.4.6/netutil/net.go#L158-L170
https://github.com/duke-git/lancet/blob/v2.3.9/netutil/net.go#L192-L205
https://github.com/duke-git/lancet/commit/835111c832939a85416d686a1e99d5fe7060c9b4
https://github.com/duke-git/lancet/issues/356
https://github.com/duke-git/lancet/pull/357
https://www.vulncheck.com/advisories/lancet-through-2.3.9-ssrf-protection-bypass-via-netutil-isinternalip
https://github.com/duke-git/lancet/issues/356

Get alerted when CVE-2026-110240 or the next vulnerability affects your stack