Security readout for executives and security teams
Plain-English summary
A malicious or compromised upstream HTTP/2 server could crash vulnerable Envoy processes by triggering an invalid connection-state transition. The impact is availability loss, not data theft or tampering. The issue is fixed in Envoy 1.19.1 and 1.18.4.
Executive priority
Treat as a high-priority availability risk for affected Envoy deployments with untrusted upstreams. Patch promptly, especially where Envoy supports critical traffic paths or customer-facing services.
Technical view
Envoy mishandles HTTP/2 GOAWAY followed by SETTINGS_MAX_CONCURRENT_STREAMS=0 in the same I/O event. With no outstanding streams, Envoy moves to CLOSED, then incorrectly attempts DRAINING, causing abnormal process termination. Affected versions are 1.19.0 and 1.18.0 through 1.18.3.
Likely exposure
Exposure is most likely where affected Envoy versions communicate over HTTP/2 with untrusted, third-party, compromised, or otherwise lower-trust upstream servers. Deployments without such upstream trust boundaries have lower practical exposure, but still need version validation.
Exploitation context
The provided sources do not report active exploitation, and KEV is false. The CVSS vector indicates network access, low complexity, no privileges, no user interaction, changed scope, and high availability impact.
Researcher notes
This is an HTTP/2 connection state-machine flaw, not a confidentiality or integrity issue. Validation should focus on version ranges, upstream trust boundaries, HTTP/2 usage, and evidence of Envoy process termination. Avoid assuming client-side exploitability from the provided sources.
Mitigation direction
- Upgrade Envoy 1.19.0 to 1.19.1 or later.
- Upgrade Envoy 1.18.x deployments to 1.18.4 or later.
- Prioritize proxies with HTTP/2 upstreams to untrusted services.
- Check Envoy advisory and version history for branch-specific guidance.
- Monitor for unexplained Envoy restarts until patched.
Validation and detection
- Inventory all deployed Envoy versions and compare against affected ranges.
- Identify HTTP/2 upstream clusters connected to lower-trust services.
- Confirm fixed versions are deployed across all proxy instances.
- Review process restart telemetry for abnormal Envoy termination patterns.
- Document any remaining affected instances and compensating controls.
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-754: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-32780 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
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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.
CVSS vector scores
1 official scoreWe 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:C/C:N/I:N/A:H3.94Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_historyCVE reference · x_refsource_MISC
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-j374-mjrw-vvp8CVE reference · x_refsource_CONFIRM
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.
Improper Check for Unusual or Exceptional Conditions
Improper Check for Unusual or Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.