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Grafana CVE-2026-21720

HIGH
Uncontrolled Resource Consumption (CWE-400)
2026-01-27 security@grafana.com
Denial Of Service Grafana
7.5
CVSS 3.1 · Vendor: grafana
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Send sustained HTTP requests to /avatar/:hash endpoint
  2. Delivery
    Spawn goroutines exceeding worker queue capacity
  3. Exploit
    Trigger handler timeouts on unbuffered channels
  4. Execution
    Accumulate blocked goroutines
  5. Impact
    Exhaust memory and crash Grafana

Vulnerability Assessment

Weakness
CWE
CWE-400
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource consumption limits
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Grafana instance with uncached avatar endpoint enabled. Attacker sends repeated requests with random hash values to /avatar/:hash endpoint. No authentication required; works against default Grafana configurations accepting remote HTTP requests.
Impact

CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None.
Exploit ScenarioDerived

An attacker could exploit this vulnerability to compromise the affected system.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Grafana is vulnerable to denial of service through resource exhaustion when processing uncached avatar requests with random hashes. Sustained requests cause goroutines to accumulate indefinitely due to timeout handling issues, eventually consuming all available memory and crashing the application. An unauthenticated remote attacker can exploit this vulnerability without user interaction to render affected Grafana instances unavailable.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 21:55 CVSS 7.5

Every uncached /avatar/:hash request spawns a goroutine that refreshes the Gravatar image. If the refresh sits in the 10-slot worker queue longer than three seconds, the handler times out and stops listening for the result, so that goroutine blocks forever trying to send on an unbuffered channel. [CVSS 7.5 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

Classified as CWE-400 (Uncontrolled Resource Consumption). Affects Grafana. Every uncached /avatar/:hash request spawns a goroutine that refreshes the Gravatar image. If the refresh sits in the 10-slot worker queue longer than three seconds, the handler times out and stops listening for the result, so that goroutine blocks forever trying to send on an unbuffered channel. Sustained traffic with random hashes keeps tripping this timeout, so goroutine count grows linearly, eventually exhausting memory and causing Grafana to crash on some systems.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Vendor (grafana) PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from Vendor (grafana).

CVSS VectorVendor: grafana

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch released
Apr 09, 2026 - 14:30 nvd
Patch available
CVE Published
Jan 27, 2026 - 09:15 nvd
HIGH 7.5

DescriptionCVE.org

Every uncached /avatar/:hash request spawns a goroutine that refreshes the Gravatar image. If the refresh sits in the 10-slot worker queue longer than three seconds, the handler times out and stops listening for the result, so that goroutine blocks forever trying to send on an unbuffered channel. Sustained traffic with random hashes keeps tripping this timeout, so goroutine count grows linearly, eventually exhausting memory and causing Grafana to crash on some systems.

Executive ViewAI

Why It Matters

A resource exhaustion vulnerability in the avatar refresh mechanism can cause application goroutines to block indefinitely, potentially degrading service availability and consuming memory resources. This affects any system relying on uncached Gravatar image requests and could impact user-facing services and API responsiveness.

Business Impact: High
Compensating Controls

Implement request-level timeouts shorter than 3 seconds to prevent queue buildup; enable aggressive HTTP caching headers for avatar responses (Cache-Control with extended TTL); implement circuit breaker patterns to fail-fast on slow Gravatar responses; configure WAF rules to rate-limit repeated /avatar/:hash requests from single sources; deploy connection pooling limits on outbound Gravatar requests; consider disabling dynamic avatar refresh and serving static default avatars instead; monitor goroutine count and memory consumption for early warning signs of resource exhaustion.

Threat Intelligence Overview

EPSS Score
0.0%
Top 95% exploitable
Data Quality
5 sources
Confidence: Medium
NVD CVE.org EPSS Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)CVE.org

cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:*
cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:grafana:grafana:12.3.0:*:*:*:-:*:*:*
cpe:2.3:a:grafana:grafana:12.3.0:*:*:*:enterprise:*:*:*

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Vendor StatusVendor

SUSE

Severity: High
Product Status
Container suse/manager/5.0/x86_64/server:latest Affected
SUSE Linux Enterprise Module for Package Hub 15 SP7 Fixed
SUSE Manager Client Tools 15 Fixed
SUSE Manager Client Tools for SLE Micro 5 Fixed
SUSE Manager Proxy LTS 4.3 Fixed

References

Advisories & patches
ADVISORY https://vuldb.com/vuln/342969 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1013/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1037/ REF https://access.redhat.com/security/cve/CVE-2026-21720 REF https://bugzilla.redhat.com/show_bug.cgi?id=2433226 REF https://grafana.com/security/security-advisories/CVE-2026-21720 REF https://grafana.com/security/security-advisories/cve-2026-21720 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21720.json

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