CVE-2026-56742
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
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.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
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.
- Record
CVE-2026-56742- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
EUVDEUVD-2026-44773
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.
- Record
EUVD-2026-44773- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w7c2-w76w-5hmj
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
Impact
In Cilium clusters using Gateway API, users with permissions to create or update namespaced HTTPRoutes can mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism.
Gateway API functionality is disabled by default.
Patches
This issue affects:
- Cilium v1.19 from v1.19.0 to v1.19.4 inclusive
- Cilium v1.18 from v1.18.0 to v1.18.10 inclusive
- All versions of Cilium before v1.17.17
This issue is patched in:
- Cilium v1.19.5
- Cilium v1.18.11
- Cilium v1.17.17
Workarounds
There is no workaround to this issue. Users of this feature who are unable to upgrade can mitigate the risk by ensuring that RBAC permissions to create HTTPRoute objects are only granted to cluster admins.
Acknowledgements
The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @galanko for reporting the issue and @mhofstetter for their work on triaging and remediating this issue.
For more information
If you have any questions or comments about this advisory, please reach out on Slack.
If you think you have found a vulnerability affecting Cilium, we strongly encourage you to report it to our security mailing list at [email protected]. This is a private mailing list for the Cilium security team, and your report will be treated as top priority.
- Record
GHSA-w7c2-w76w-5hmj- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-56742- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L - CVSS 3.1
- 8.9 High
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
OSV
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
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.
- Record
CVE-2026-56742- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
OSVGHSA-w7c2-w76w-5hmj
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
Impact
In Cilium clusters using Gateway API, users with permissions to create or update namespaced HTTPRoutes can mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism.
Gateway API functionality is disabled by default.
Patches
This issue affects:
- Cilium v1.19 from v1.19.0 to v1.19.4 inclusive
- Cilium v1.18 from v1.18.0 to v1.18.10 inclusive
- All versions of Cilium before v1.17.17
This issue is patched in:
- Cilium v1.19.5
- Cilium v1.18.11
- Cilium v1.17.17
Workarounds
There is no workaround to this issue. Users of this feature who are unable to upgrade can mitigate the risk by ensuring that RBAC permissions to create HTTPRoute objects are only granted to cluster admins.
Acknowledgements
The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @galanko for reporting the issue and @mhofstetter for their work on triaging and remediating this issue.
For more information
If you have any questions or comments about this advisory, please reach out on Slack.
If you think you have found a vulnerability affecting Cilium, we strongly encourage you to report it to our security mailing list at [email protected]. This is a private mailing list for the Cilium security team, and your report will be treated as top priority.
- Record
GHSA-w7c2-w76w-5hmj- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L - Weakness
- CWE-862
- Updated
- 2026-11-02
Show 4 moreShow less
OSVBIT-cilium-2026-56742 No score
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
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.
- Record
BIT-cilium-2026-56742- Updated
- 2026-11-02
OSVBIT-cilium-operator-2026-56742 No score
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
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.
- Record
BIT-cilium-operator-2026-56742- Updated
- 2026-11-02
OSVBIT-hubble-relay-2026-56742 No score
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces
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.
- Record
BIT-hubble-relay-2026-56742- Updated
- 2026-11-02
OSVGO-2026-6596 No score
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces in github.com/cilium/cilium
Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces in github.com/cilium/cilium
- Record
GO-2026-6596- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
github.com/cilium/ciliumGo |
before 1.17.17 | 1.17.17 |
github.com/cilium/ciliumCiliumGo |
1.18.0 up to 1.18.11 | 1.18.11 |
github.com/cilium/ciliumGo |
1.19.0 up to 1.19.5 | 1.19.5 |
ciliumBitnami |
before 1.17.17, 1.18.0 up to 1.18.11, 1.19.0 up to 1.19.5 | 1.17.171.18.111.19.5 |
cilium-operatorBitnami |
before 1.17.17, 1.18.0 up to 1.18.11, 1.19.0 up to 1.19.5 | 1.17.171.18.111.19.5 |
hubble-relayBitnami |
before 1.17.17, 1.18.0 up to 1.18.11, 1.19.0 up to 1.19.5 | 1.17.171.18.111.19.5 |
github.com/cilium/ciliumGo |
before 1.17.17, 1.18.0 up to 1.18.11, 1.19.0 up to 1.19.5 | 1.17.171.18.111.19.5 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-56742 is a medium vulnerability (CVSS 5.9) in Cilium, published July 15, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 7th percentile. Fixed in github.com/cilium/cilium 1.17.17.
References
github.com/cilium/cilium/security/advisories/GHSA-w7c2-w76w-5hmj