Is there an existing issue for this?

• I have searched the existing issues

Version

equal or higher than v1.17.5 and lower than v1.18.0

What happened?

The Cilium agent is unable to establish an authenticated BGP session.

Could the MD5 crypto missing? or some BGP dependency got updated and wrecked the MD5 auth mechanism.

How can we reproduce the issue?

1. Install Cilium configuring BGP to use a password (RFC-2385)

Cilium Version

1.17.4
1.17.5

Kernel Version

6.14.9-300.fc42.x86_64

Kubernetes Version

v1.31.2

Regression

v1.17.3

Sysdump

cilium-sysdump-20250711-032514.zip

Relevant log output

time="2025-07-10T23:20:53.136122987Z" level=warning msg="failed to set md5" Err="protocol not available" Key="fdeb:e7:b88:3::1" Topic=Peer asn=64513 component=gobgp.BgpServerInstance subsys=bgp-control-plane
[...]
time="2025-07-10T23:20:53.13640939Z" level=warning msg="failed to unset md5" Err="protocol not available" Key=172.16.38.1 Topic=Peer asn=64513 component=gobgp.BgpServerInstance subsys=bgp-control-plane
[...]
time="2025-07-10T23:20:53.136479124Z" level=warning msg="failed to set md5" Err="protocol not available" Key=172.16.38.1 Topic=Peer asn=64513 component=gobgp.BgpServerInstance subsys=bgp-control-plane

Anything else?

The issue is NOT present on 1.17.3

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