etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline
Assessment
- Severity
- Important
- CVSS base score
- Not published
- Impact
- Not stated
- EPSS, next 30 days
- Not scored yet
- Public exploit code
- No Nuclei template lists it
- Exploitability
- Not assessed
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Mariner
- Weakness
- CWE-770: Allocation of Resources Without Limits or Throttling
- Issued by
- GitHub_M
- Published
- 23 Aug 2026 · August 2026
- Last revised
- 23 Aug 2026
Updates that fix it
0 KBsNo KB listed
MSRC lists no downloadable update, which usually means a service-side fix or a release-notes update. Check the MSRC advisory.
Affected products
7 affected products
- azl3 cert-manager 1.12.15-11 on Azure Linux 3.0
- azl3 cloud-provider-kubevirt 0.5.1-6 on Azure Linux 3.0
- azl3 flannel 0.24.2-29 on Azure Linux 3.0
- azl3 keda 2.14.1-16 on Azure Linux 3.0
- azl3 kube-vip-cloud-provider 0.0.10-7 on Azure Linux 3.0
- azl3 kubernetes 1.30.10-27 on Azure Linux 3.0
- azl3 prometheus-adapter 0.12.0-7 on Azure Linux 3.0
What changed
First observed 14 Oct 2026- 23 Oct 2026 · 09:33:49 UTC Public exploit codeUnknown: exploit-code evidence is incomplete or retained → No Nuclei template listed
- 23 Oct 2026 · 09:33:49 UTC CISA KEVUnknown: catalog evidence is incomplete or retained → Not listed in the collected catalog
- 23 Oct 2026 · 09:33:49 UTC Source coverage: public-exploit-codeIncomplete → Current
- 23 Oct 2026 · 09:33:49 UTC Source coverage: first-epssIncomplete → Current
- 23 Oct 2026 · 09:33:49 UTC Source coverage: cisa-kevIncomplete → Current
- 23 Oct 2026 · 09:33:49 UTC Source coverage: msrc-cvrfIncomplete → Current
- 23 Oct 2026 · 08:31:50 UTC Public exploit codeNo Nuclei template listed → Unknown: exploit-code evidence is incomplete or retained
- 23 Oct 2026 · 08:31:50 UTC CISA KEVNot listed in the collected catalog → Unknown: catalog evidence is incomplete or retained
- 23 Oct 2026 · 08:31:50 UTC Source coverage: public-exploit-codeCurrent → Incomplete
- 23 Oct 2026 · 08:31:50 UTC Source coverage: first-epssCurrent → Incomplete
- 23 Oct 2026 · 08:31:50 UTC Source coverage: cisa-kevCurrent → Incomplete
- 23 Oct 2026 · 08:31:50 UTC Source coverage: msrc-cvrfCurrent → Incomplete
Show 2 more recent changes
- 18 Oct 2026 · 14:54:30 UTCLink: August 2026 → /security?release=2026-Aug#cves
- 14 Oct 2026 · 11:22:42 UTCSource coverage: msrc-cvrf Incomplete → Current
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Explore global source statements, affected packages and advisory history for CVE-2026-73500. The catalog has a separate collection scope from Microsoft release records.
Collected exploitation and prediction evidence
Risk source coverageCISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.
No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.
cve-program · CVE-2026-73500
Publishedetcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline
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.
- Source published
- 12 Aug 2026 21:22:25 UTC
- Source modified
- 13 Aug 2026 17:53:16 UTC
- Observed here
- 23 Oct 2026 15:48:27 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS 4.0 · 8.7 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
nvd · CVE-2026-73500
Publishedetcd 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 cl…
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.
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Awaiting Analysis
Weakness classifications: CWE-770
Original publisher date fields
published: 2026-08-12T22:17:17.290
lastModified: 2026-10-24T15:10:00.190
- Source published
- 12 Aug 2026 22:17:17 UTC
- Source modified
- 24 Oct 2026 15:10:00 UTC
- Observed here
- 25 Oct 2026 15:19:09 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS 4.0 · [email protected] · Secondary · 8.7 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
osv · GHSA-6vch-q96h-7gc3
Publishedetcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline
### 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
- Source published
- 24 Jul 2026 22:40:16 UTC
- Source modified
- 10 Sep 2026 03:51:10 UTC
- Observed here
- 24 Oct 2026 13:19:41 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS_V4 · 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
Publisher rating · HIGH
osv · GO-2026-6107
PublishedUnbounded TLS handshake goroutines in go.etcd.io/etcd/client/pkg/v3
In go.etcd.io/etcd/client/pkg/v3 before 3.5.33, 3.6.14, and 3.7.1, TLS handshakes on listeners created by NewTLSListener do not enforce a handshake deadline. An unauthenticated network attacker who connects to an etcd TLS listener without sending a ClientHello causes a goroutine and a tracking map entry to block indefinitely. Opening many such connections exhausts memory, leading to a denial of service.
- Source published
- 18 Aug 2026 16:38:10 UTC
- Source modified
- 19 Aug 2026 21:41:59 UTC
- Observed here
- 24 Oct 2026 13:19:41 UTC
- Source terms
- OSV · upstream source license applies
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.