Cilium with misconfigured toGroups in policies can lead to unrestricted egress traffic

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.0 · CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2025-64715: 0.18% estimated exploitation activity in the next 30 days; percentile 8.04 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact CiliumNetworkPolicys which use egress.toGroups.aws.securityGroupsIds to reference AWS security group IDs that do not exist or are not attached to any network interface may unintentionally allow broader outbound access than intended by the policy authors. In such cases, the toCIDRset section of the derived policy is not generated, which means outbound traffic may be permitted to more destinations than originally intended. Patches This issue has been patched in: Cilium v1.18.4 Cilium v1.17.10 Cilium v1.16.17 This issue affects: - Cilium v1.18 between v1.18.0 and v1.18.3 inclusive - Cilium v1.17 between v1.17.0 and v1.17.9 inclusive - Cilium v1.16.16 and below Workarounds There is no workaround to this issue. Acknowledgements The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @SeanEmac for reporting this issue and to @fristonio for the patch. For more information If you think you have found a vulnerability affecting…

Published by the source

1 Dec 2025, 18:59 UTC

Last modified by the source

2 Jul 2026, 20:21 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-38pp-6gcp-rqvm

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# Patch Next advisory brief: CVE-2025-64715

Advisory: Cilium with misconfigured toGroups in policies can lead to unrestricted egress traffic
IDs: CVE-2025-64715, GHSA-38pp-6gcp-rqvm
Record: https://patchnext.com/advisories/cve-2025-64715 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/cilium/cilium 1.18.4, 1.17.10, 1.16.17. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cilium/cilium: affected >= 1.18.0, < 1.18.4; < 1.16.17; >= 1.17.0, < 1.17.10; fixed in 1.17.10, 1.16.17, 1.18.4

## Suggested inspection (read-only)
- Go github.com/cilium/cilium: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/cilium/cilium.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-38pp-6gcp-rqvm (GitHub-reviewed advisory GHSA-38pp-6gcp-rqvm lists affected ranges: Go github.com/cilium/cilium >=1.18.0 =0 =1.17.0 <1.17.10)

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