etcd-io etcd up to 3.5.32/3.6.13/3.7.0 TLS Listener listener_tls.go tls.Conn.Handshake infinite loop

Summaryinfo

A vulnerability was found in etcd-io etcd up to 3.5.32/3.6.13/3.7.0. It has been declared as problematic. This vulnerability affects the function tls.Conn.Handshake of the file client/pkg/transport/listener_tls.go of the component TLS Listener. The manipulation results in infinite loop. This vulnerability is cataloged as CVE-2026-73500. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in etcd-io etcd up to 3.5.32/3.6.13/3.7.0. Affected is the function tls.Conn.Handshake of the file client/pkg/transport/listener_tls.go of the component TLS Listener. The manipulation with an unknown input leads to a infinite loop vulnerability. CWE is classifying the issue as CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-73500 since 08/12/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 3.5.33, 3.6.14 or 3.7.1 eliminates this vulnerability.

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Productinfo

Vendor

• etcd-io

Name

• etcd

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.5.7
• 3.5.8
• 3.5.9
• 3.5.10
• 3.5.11
• 3.5.12
• 3.5.13
• 3.5.14
• 3.5.15
• 3.5.16
• 3.5.17
• 3.5.18
• 3.5.19
• 3.5.20
• 3.5.21
• 3.5.22
• 3.5.23
• 3.5.24
• 3.5.25
• 3.5.26
• 3.5.27
• 3.5.28
• 3.5.29
• 3.5.30
• 3.5.31
• 3.5.32
• 3.6
• 3.6.0
• 3.6.1
• 3.6.2
• 3.6.3
• 3.6.4
• 3.6.5
• 3.6.6
• 3.6.7
• 3.6.8
• 3.6.9
• 3.6.10
• 3.6.11
• 3.6.12
• 3.6.13
• 3.7.0

Website

• Product: https://github.com/etcd-io/etcd/

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