Security readout for executives and security teams
Plain-English summary
An unauthenticated attacker could repeatedly request uncached Grafana avatars, causing background tasks to accumulate and consume memory until some systems crash. This threatens dashboard availability, not data confidentiality or integrity. The supplied version records are inconsistent and do not establish a reliable affected-version range.
Executive priority
Prioritize exposed Grafana systems because successful abuse could interrupt monitoring during operational or security incidents. Establish the actual affected-version range from Grafana's advisory, reduce anonymous endpoint exposure, and schedule vendor-supported remediation promptly. There is no supplied evidence of active exploitation.
Technical view
Timed-out /avatar/:hash requests stop receiving results while refresh goroutines later attempt delivery through an unbuffered channel. Those goroutines remain blocked indefinitely. Random uncached hashes can repeatedly trigger the leak, producing linear goroutine growth, memory exhaustion, and denial of service.
Likely exposure
Potential exposure exists where a Grafana deployment serves /avatar/:hash to untrusted users. Internet-accessible or anonymously reachable instances face greater risk. The bundle lists repeated version 3.0.0 records marked unaffected, so deployment-specific exposure cannot be confirmed from the supplied data.
Exploitation context
The weakness is remotely reachable, requires no authentication or user interaction, and has low stated attack complexity. CVSS is 7.5. The bundle reports KEV as false and provides no cited evidence of active exploitation; exploit prevalence is therefore unknown.
Researcher notes
The failure combines bounded refresh capacity, a three-second handler timeout, and an unbuffered result channel without cancellation-safe delivery. The leaked resource is the sending goroutine. Confirm the implementation and fixed versions from vendor materials; the supplied affected-product records are duplicated and marked unaffected, limiting version-level conclusions.
Mitigation direction
- Review Grafana's advisory for confirmed affected versions and vendor-approved remediation.
- Apply the vendor-supported fixed release or mitigation when identified.
- Restrict anonymous access to the avatar endpoint where operationally acceptable.
- Rate-limit abnormal requests containing numerous distinct avatar hashes.
- Monitor memory and goroutine growth until remediation is confirmed.
Validation and detection
- Inventory Grafana editions and exact versions across all environments.
- Determine whether /avatar/:hash is reachable without authentication or from the internet.
- Compare installed versions directly with Grafana's current advisory.
- Review telemetry for high-cardinality avatar requests, rising goroutines, or memory exhaustion.
- Confirm resource usage remains stable after remediation under authorized defensive testing.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-400: Exact CWE lookup
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Open ATT&CK lookupCWE-703: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-772: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-21720 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6GRAFANACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-01-27T10:01:10.677Z: Reported to Red Hat.
- 2026-01-27T09:07:04.758Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://grafana.com/security/security-advisories/cve-2026-21720CVE reference, GRAFANA · vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-21720CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2433226CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21720.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Check or Handling of Exceptional Conditions
Improper Check or Handling of Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Missing Release of Resource after Effective Lifetime
Missing Release of Resource after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.