CVE-2026-73500: etcd `tlsListener.acceptLoop` Spawns Unbounded Handshake Goroutines Vulnerability

HIGH
Advisory Identifier: GHSA-6vch-q96h-7gc3
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CWE-770
Published
Advisory Summary

CVE-2026-73500 is a HIGH `tlslistener.acceptloop` spawns unbounded handshake goroutines vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting etcd libraries in the Go ecosystem. The issue involves `tlslistener.acceptloop` spawns unbounded handshake goroutines with no deadline. Remediation is available by upgrading affected packages to version 3.7.1, 3.6.14, 3.5.33.

CVE-2026-73500 at a Glance

CVE Identifier CVE-2026-73500
GHSA Identifier GHSA-6vch-q96h-7gc3
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product etcd
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2026-73500

To remediate this vulnerability, upgrade all affected etcd dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

go.etcd.io/etcd/v3 fixed: 3.7.1 
Upgrade go.etcd.io/etcd/v3 to 3.7.1
go.etcd.io/etcd/v3 fixed: 3.6.14 
Upgrade go.etcd.io/etcd/v3 to 3.6.14
go.etcd.io/etcd/v3 fixed: 3.5.33 
Upgrade go.etcd.io/etcd/v3 to 3.5.33
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for go.etcd.io/etcd/v3

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-73500, inspect your project dependencies for etcd:

inspect dependencies for go.etcd.io/etcd/v3

Analyze the terminal output to locate any version of etcd in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.7.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In etcd, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact _What kind of vulnerability is it? Who is impacted?_ A network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. Each connection spawns a goroutine in the etcd server process that blocks indefinitely inside tls.Conn.Handshake(), and each is tracked in the pending map. Unbounded goroutine and map growth exhausts memory in the etcd process, causing loss of availability for the etcd cluster (and, when etcd backs Kubernetes, the control plane). ### Patches _Has the problem been patched? What versions should users upgrade to?_ This vulnerability is patched in the following versions: - etcd 3.7.1 - etcd 3.6.14 - etcd 3.5.33 ### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ If upgrading is not immediately possible, then restrict network access. Limit which hosts can reach etcd's client (gRPC) port via firewall rules or network policy, reducing who can attempt exploitation. ### Reporter VMware By Broadcom

CVE-2026-73500 Affected etcd Versions

3 component(s)
Fixed Versions:
3.7.13.6.143.5.33
Product / Package Ecosystem Affected Versions Fixed Version
go.etcd.io/etcd/v3
golang/go.etcd.io/etcd/v3
Go
≥ 3.7.0-alpha.0
< 3.7.1
3.7.1
go.etcd.io/etcd/v3
golang/go.etcd.io/etcd/v3
Go
≥ 3.6.0
< 3.6.14
3.6.14
go.etcd.io/etcd/v3
golang/go.etcd.io/etcd/v3
Go
< 3.5.33
3.5.33

References

etcd Release RELEASE
https://github.com/etcd-io/etcd/releases/tag/v3.7.1
GitHub Advisory / Wiki ADVISORY
https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3
etcd Source Repository REPOSITORY
https://github.com/etcd-io/etcd/pull/22130
Security Fix Commit FIX COMMIT
https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2
Security Fix Commit FIX COMMIT
https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057
etcd Source Repository REPOSITORY
https://github.com/etcd-io/etcd
etcd Release RELEASE
https://github.com/etcd-io/etcd/releases/tag/v3.5.33
etcd Release RELEASE
https://github.com/etcd-io/etcd/releases/tag/v3.6.14

Frequently Asked Questions

What is CVE-2026-73500?
CVE-2026-73500 is a security vulnerability in etcd involving `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline under CWE-770: Allocation of Resources Without Limits or Throttling.
Which etcd versions are affected?
Affected versions include releases prior to 3.7.1, 3.6.14, 3.5.33 across affected packages: go.etcd.io/etcd/v3.
What version fixes CVE-2026-73500?
Upgrading to 3.7.1, 3.6.14, 3.5.33 (or the latest patched release for your respective branch) resolves the vulnerability.
Is go.etcd.io/etcd/v3 affected?
Yes, go.etcd.io/etcd/v3 is affected in releases prior to 3.7.1, 3.6.14, 3.5.33. Upgrade your dependency to 3.7.1, 3.6.14, 3.5.33 or later.
What CWE is associated with CVE-2026-73500?
CVE-2026-73500 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check Go dependencies for CVE-2026-73500?
Run the dependency tree command: 'inspect dependencies for go.etcd.io/etcd/v3'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6vch-q96h-7gc3",
  "modified" : "2026-08-12T21:22:30Z",
  "published" : "2026-07-24T22:40:16Z",
  "aliases" : [ "CVE-2026-73500" ],
  "summary" : "etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline",
  "details" : "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nA network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. Each connection spawns a goroutine in the etcd server process that blocks indefinitely inside tls.Conn.Handshake(), and each is tracked in the pending map. Unbounded goroutine and map growth exhausts memory in the etcd process, causing loss of availability for the etcd cluster (and, when etcd backs Kubernetes, the control plane).\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nThis vulnerability is patched in the following versions:\n\n- etcd 3.7.1\n- etcd 3.6.14\n- etcd 3.5.33\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nIf upgrading is not immediately possible, then restrict network access. Limit which hosts can reach etcd's client (gRPC) port via firewall rules or network policy, reducing who can attempt exploitation.\n\n### Reporter\n\nVMware By Broadcom",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
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  } ],
  "references" : [ {
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    "type" : "WEB",
    "url" : "https://github.com/etcd-io/etcd/pull/22130"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/etcd-io/etcd"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/etcd-io/etcd/releases/tag/v3.5.33"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/etcd-io/etcd/releases/tag/v3.6.14"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/etcd-io/etcd/releases/tag/v3.7.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T22:40:16Z",
    "nvd_published_at" : null
  }
}