Flannel is a Container Network Interface (CNI) plug-in that creates a virtual network for containers using Virtual Private Cloud (VPC). Use Flannel to enable pod-to-pod communication within an ACK cluster. This topic describes the release notes for Flannel.
Overview
The Flannel CNI plug-in provided by Container Service for Kubernetes (ACK) allocates a pod CIDR block that is independent of the VPC CIDR block. Flannel forwards packets based on the VPC route table, which eliminates the need for tunneling technologies such as Virtual extensible LAN (VXLAN) and improves network communication efficiency. For more information, see Network overview.
Usage notes
Flannel is a simple and stable open source CNI plug-in. When used with VPC, Flannel gives your clusters and containers access to high-performance, stable networks. For more information, see flannel.
Version compatibility
The following table shows which Flannel version is active for each Kubernetes version range.
| Kubernetes version |
Active Flannel version |
| 1.35 or later |
v0.28.0.6 |
| 1.26 to 1.34 |
v0.15.1.23-33d25c1-aliyun |
| Earlier than 1.26 |
v0.15.1.22-20a397e6-aliyun |
Release notes
March 2026
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.28.0.6 |
registry-cn-hangzhou.ack.aliyuncs.com/acs/flannel:v0.28.0.6 |
March 2, 2026 |
- Upgraded the cni-plugin version to support nftables mode switching.
- Fixed multiple CVE vulnerabilities.
|
Clusters running Kubernetes 1.35 or later are upgraded to this version. Clusters running Kubernetes earlier than 1.35 continue to use v0.15.1.23-33d25c1-aliyun. |
May 2024
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.23-33d25c1-aliyun |
registry-cn-hangzhou.ack.aliyuncs.com/acs/flannel:v0.15.1.23-33d25c1-aliyun |
May 20, 2024 |
Improved Flannel compatibility on Windows. |
Clusters running Kubernetes 1.26 or later are upgraded to this version. Clusters running Kubernetes earlier than 1.26 continue to use v0.15.1.22-20a397e6-aliyun. |
December 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.22-20a397e6-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.22-20a397e6-aliyun |
December 6, 2022 |
Changed the DaemonSet update policy from OnDelete to RollingUpdate. Previously, manual changes to the Flannel YAML did not take effect until you deleted and recreated the Flannel pods. Now, changes are automatically applied to all Flannel pods through a rolling update. For more information, see DaemonSet update strategy. |
After you update Flannel to this version, if you manually modify the YAML file of Flannel, the modifications are automatically applied to all Flannel pods through a rolling update. You do not need to delete Flannel pods to trigger their recreation. |
October 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.19-d460293f-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.19-d460293f-aliyun |
October 27, 2022 |
- Added compatibility for scenarios where the CNIVersion field is missing.
- Fixed the CVE-2021-45079 vulnerability.
|
No impact on workloads. |
September 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.18-6f371e73-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.18-6f371e73-aliyun |
September 26, 2022 |
Disabled Node Informer by default to improve performance. |
No impact on workloads. |
August 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.13-941db231-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.13-941db231-aliyun |
August 29, 2022 |
Fixed the CVE-2022-37434 vulnerability. |
No impact on workloads. |
July 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.11-7e95fe23-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.11-7e95fe23-aliyun |
July 28, 2022 |
Changed the default IP address cache directory to /var/run to prevent IP leaks caused by node restarts. |
No impact on workloads. |
May 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.8-1634a106-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.8-1634a106-aliyun |
May 10, 2022 |
Fixed the CVE-2022-28391 vulnerability. |
No impact on workloads. |
April 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.6-a320565c-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.6-a320565c-aliyun |
April 8, 2022 |
Added an init container for Flannel installation. |
No impact on workloads. |
January 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.5-11d1c700-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.5-11d1c700-aliyun |
January 25, 2022 |
Added support for ARM64 instances. |
No impact on workloads. |
December 2021
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.4-e02c8f12-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.4-e02c8f12-aliyun |
December 1, 2021 |
- Updated the API version for Authorization and other resources to support Kubernetes 1.22.
- Added support for exposing services via HostPort.
- Enabled hairpin mode by default. Previously, hairpin mode was disabled by default. For information about enabling hairpin mode on earlier versions, see How do I enable a pod to access a Service that is used to expose the pod?
|
No impact on workloads. |
May 2021
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.13.0.1-466064b-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.13.0.1-466064b-aliyun |
May 24, 2021 |
- Added iptables support for compatibility with CentOS 8 and Alibaba Cloud Linux 3 and later.
- Added proactive checks and automatic correction of IP forwarding configurations.
|
No impact on workloads. |
August 2019
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.11.0.2-g6e46593e-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.11.0.2-g6e46593e-aliyun |
August 2, 2019 |
Fixed an issue where source IP addresses were not retained after a Flannel upgrade. |
No impact on workloads. If a container name conflict occurs during the upgrade and causes the upgrade to fail, see Troubleshoot component exceptions to resolve it. |