CVE-2026-21720: Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• grafana grafana3.0.0 and later · before 11.6.9
• grafana grafana12.0.0 and later · before 12.0.8
• grafana grafana12.1.0 and later · before 12.1.5
• grafana grafana12.2.0 and later · before 12.2.3
• grafana grafana12.3.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GRAFANA). Independent of NVD's CPE analysis and usually ahead of it.

• Grafana grafana/grafana

  • 3.0.0 and later · before 11.6.9affected · semver
  • 3.0.0 and later · before 12.0.8affected · semver
  • 3.0.0 and later · before 12.1.5affected · semver
  • 3.0.0 and later · before 12.2.3affected · semver
  • 3.0.0 and later · before 12.3.1affected · semver

• Grafana grafana/grafana-enterprise

  • 3.0.0 and later · before 11.6.9affected · semver
  • 3.0.0 and later · before 12.0.8affected · semver
  • 3.0.0 and later · before 12.1.5affected · semver
  • 3.0.0 and later · before 12.2.3affected · semver
  • 3.0.0 and later · before 12.3.1affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2021-39226Snapshot authentication bypass in grafanaKEV
  89Now
• CVE-2021-43798Grafana path traversalKEV
  87Now
• CVE-2024-9264Grafana SQL Expressions allow for remote code execution
  66This week

Published before and after this one in the same product

• ← EarlierCVE-2025-6197Jul 18, 2025 · An open redirect vulnerability has been identified in Grafana OSS organization switching functionality.
  37Monitor
• ← EarlierCVE-2025-41115Nov 21, 2025 · Incorrect privilege assignment
  44Plan
• Later →CVE-2026-21721Jan 27, 2026 · Dashboard Permissions Scope Bypass Enables Cross‑Dashboard Privilege Escalation
  32Monitor

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1function expand(node) {2  return node.children.map(expand);3}

1const MAX_DEPTH = 32;2function expand(node, depth = 0) {3  if (depth > MAX_DEPTH) throw new Error("too deep");4  return node.children.map((c) => expand(c, depth + 1));5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.