CVE-2026-73500

etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline

Description

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.

Scores

Weaknesses (CWE)

• CWE-770

Advisories

• GHSA-6vch-q96h-7gc3 — etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline
• GO-2026-6107 — Unbounded TLS handshake goroutines in go.etcd.io/etcd/client/pkg/v3

European references

• ENISA EUVD · EUVD-2026-57642
• GCVE · GCVE-0-2026-73500

CERT-FR advisories

• CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr

Affected products

References

• https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3
• https://github.com/etcd-io/etcd/pull/22130
• https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2
• https://github.com/etcd-io/etcd/commit/89ff6d50796049d4f1136915ba21504b76e7e372
• https://github.com/etcd-io/etcd/commit/8e4dd0679a2c6b095d2a32a749fda2521c7809a3
• https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057
• https://github.com/etcd-io/etcd/releases/tag/v3.5.33
• https://github.com/etcd-io/etcd/releases/tag/v3.6.14
• https://github.com/etcd-io/etcd/releases/tag/v3.7.1

Sources