CVE-2026-33726 [Medium] | Security Bypass in Cilium

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Prior to versions 1.17.14, 1.18.8, and 1.19.2, Ingress Network Policies are not enforced for traffic from pods to L7 Services (Envoy, GAMMA) with a local backend on the same node, when Per-Endpoint Routing is enabled and BPF Host Routing is disabled. Per-Endpoint Routing is disabled by default, but is automatically enabled in deployments using cloud IPAM, including Cilium ENI on EKS (`eni.enabled`), AlibabaCloud ENI (`alibabacloud.enabled`), Azure IPAM (`azure.enabled`, but not AKS BYOCNI), and some GKE deployments (`gke.enabled`; managed offerings such as GKE Dataplane V2 may use different defaults). It is typically not enabled in tunneled deployments, and chaining deployments are not affected. In practice, Amazon EKS with Cilium ENI mode is likely the most common affected environment. Versions 1.17.14, 1.18.8, and 1.19.2 contain a patch. There is currently no officially verified or comprehensive workaround for this issue. The only option would be to disable per-endpoint routes, but this will likely cause disruptions to ongoing connections, and potential conflicts if running in cloud providers.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-03-27	—	0.01%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-03-27

—

0.01%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.4	3.1	MEDIUM	`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.3	2.7	[email protected]
4.3	3.1	MEDIUM	`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.8	1.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.4

3.1

MEDIUM

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N Click to expand

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.3

2.7

[email protected]

4.3

3.1

MEDIUM

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.8

1.4

[email protected]

Affected software / configurations for CVE-2026-33726

Vendor	Product	Version	Raw CPE
cilium	cilium	< 1.17.14	cpe:2.3:a:cilium:cilium::::::::
cilium	cilium	>= 1.18.0, < 1.18.8	cpe:2.3:a:cilium:cilium::::::::
cilium	cilium	>= 1.19.0, < 1.19.2	cpe:2.3:a:cilium:cilium::::::::

References for CVE-2026-33726

URL	Tags
https://docs.cilium.io/en/stable/network/concepts/routing/#routing	Technical Description
https://docs.cilium.io/en/stable/network/kubernetes/policy/#network-policy	Technical Description
https://docs.cilium.io/en/stable/network/servicemesh/l7-traffic-management	Technical Description
https://docs.cilium.io/en/stable/operations/performance/tuning/#ebpf-host-routing	Technical Description
https://github.com/cilium/cilium/pull/44693	Issue Tracking Patch
https://github.com/cilium/cilium/security/advisories/GHSA-hxv8-4j4r-cqgv	Patch Vendor Advisory

URL

CVE-2026-33726 | Cilium L7 proxy may bypass Kubernetes NetworkPolicy for same-node traffic

Exploit prediction scoring system (EPSS) score for CVE-2026-33726

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33726

Weakness enumeration for CVE-2026-33726

GitHub Security Advisory for CVE-2026-33726

Affected software / configurations for CVE-2026-33726

References for CVE-2026-33726