mediumCVSS 4.3Vulnerability

CVE-2026-49856

## Summary The network domain has a central SSRF authorization policy that blocks private, loopback, link-local, and reserved targets unless an explicit authorization object allows private network access. The policy is enforced by raw HTTP/TCP/TLS RTT tools, but the ICMP probe and traceroute tools resolve the target and invoke the native ICMP/traceroute sink directly. An MCP client with access to an active network domain can therefore ask the jshookmcp server to probe internal addresses such as 10.0.0.1 even when local SSRF access is disabled for the other raw network tools. This exposes an internal reachability and route mapping primitive from the server network position. ## Affected code Current main https://github.com/vmoranv/jshookmcp/commit/d309c395738638e384c28c0f599b47b2213ab595 and npm package @jshookmcp/jshook 0.3.1 both contain the issue. - src/server/domains/network/handlers/raw-latency-handlers.ts:61-66: network_rtt_measure parses optional authorization and calls resolveAuthorizedTransportTarget before probing. - src/server/domains/network/handlers/raw-latency-handlers.ts:185-190: network_latency_stats uses the same authorization guard. - src/server/domains/network/handlers/raw-latency-handlers.ts:123-139: network_traceroute resolves target with resolveHostname and calls traceroute without an authorization policy check. - src/server/domains/network/handlers/raw-latency-handlers.ts:240-257: network_icmp_probe resolves target with resolveHostname and calls icmpProbe without an authorization policy check. - src/server/domains/network/handlers/raw-latency-handlers.ts:408-416: resolveHostname returns IPv4 literals directly and otherwise performs DNS A lookup without checking private, loopback, link-local, or reserved ranges. - src/utils/network/ssrf-policy.ts:244-316: the central policy blocks private targets unless explicit authorization or ALLOW_LOCAL_SSRF=true is set. ## Reproduction Used a focused regression test against the real handleCallTool and

Properties

severity
medium
summary
@jshookmcp/jshook: ICMP probe and traceroute skip local-network SSRF authorization
epss_score
0.00209
cvss_score
4.3
ghsa_published
2026-07-01T18:14:57Z
source_url
https://github.com/advisories/GHSA-c5r6-m4mr-8q5j
ghsa_updated
2026-07-01T18:14:58Z
ghsa_id
GHSA-c5r6-m4mr-8q5j
cve_id
CVE-2026-49856
cvss_vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
is_ghsa_only
false
epss_percentile
0.11365

Related Entities (5)

ENRICHED_BY (1)

[Source]FIRST EPSS

VULNERABLE_TO (1)

[Software]npm/@jshookmcp/jshook

AFFECTS (1)

[Software]npm/@jshookmcp/jshook

HAS_WEAKNESS (1)

[Weakness]Server-Side Request Forgery (SSRF)

REPORTED_BY (1)

[Source]GitHub Advisory Database

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CVE-2026-49856 (CVSS 4.3) — Ninja Signal Threat Intelligence | Ninja Signal