etcd is a distributed key-value store for the data of a distributed system. Prior to versions 3.5.33, 3.6.14, and 3.7.1, a network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. In client/pkg/transport/listener_tls.go, each connection handled by tlsListener.acceptLoop spawns a goroutine that blocks indefinitely inside tls.Conn.Handshake() and remains tracked in the pending map.
Unbounded goroutine and map growth can exhaust memory in the etcd process, causing loss of availability for the cluster and, when etcd backs Kubernetes, the control plane. This issue is fixed in versions 3.5.33, 3.6.14, and 3.7.1.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products
etcd-io:etcd
References 9
https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2
security-advisories@github.com
https://github.com/etcd-io/etcd/commit/89ff6d50796049d4f1136915ba21504b76e7e372
security-advisories@github.com
https://github.com/etcd-io/etcd/commit/8e4dd0679a2c6b095d2a32a749fda2521c7809a3
security-advisories@github.com
https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057
security-advisories@github.com
https://github.com/etcd-io/etcd/pull/22130
security-advisories@github.com
https://github.com/etcd-io/etcd/releases/tag/v3.5.33
security-advisories@github.com
https://github.com/etcd-io/etcd/releases/tag/v3.6.14
security-advisories@github.com
https://github.com/etcd-io/etcd/releases/tag/v3.7.1
security-advisories@github.com
https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3
security-advisories@github.com