Security readout for executives and security teams
Plain-English summary
A flaw in gRPC Swift 1.1.0 and 1.1.1 can let a remote attacker crash or disrupt a service by sending malformed requests. The available sources describe denial of service, not data theft or code execution. Business impact is availability risk for exposed Swift services using this library path.
Executive priority
Treat this as an availability-focused remediation item. It is most urgent for production services exposed to untrusted gRPC-Web clients. Current evidence does not support emergency handling for confidentiality breach or remote code execution.
Technical view
The issue is mismanaged state in GRPCWebToHTTP2ServerCodec.swift. Malformed gRPC-Web requests can trigger denial of service in affected gRPC Swift releases 1.1.0 and 1.1.1. The bundle does not provide CVSS, CWE, packet details, or a precise fixed version.
Likely exposure
Exposure is likely limited to Swift services using gRPC Swift 1.1.0 or 1.1.1, especially where gRPC-Web traffic reaches the HTTP/2 server codec from untrusted clients.
Exploitation context
The CVE states remote attackers can cause denial of service with malformed requests. The source bundle does not cite CISA KEV, active exploitation, public weaponization, or exploit availability.
Researcher notes
The public bundle is sparse: no CVSS vector, CWE, affected CPEs, detailed root cause, or fixed release is included. Analysis should stay anchored to the advisory, release notes, and OSS-Fuzz reference.
Mitigation direction
- Inventory services using gRPC Swift and identify versions 1.1.0 or 1.1.1.
- Review the GitHub advisory and release notes for the vendor-supported upgrade path.
- Prioritize internet-facing or partner-facing gRPC-Web endpoints first.
- Add request filtering or rate limiting where malformed traffic could reach affected services.
- Monitor service restarts, codec errors, and unusual malformed gRPC-Web request patterns.
Validation and detection
- Check dependency manifests and build artifacts for gRPC Swift 1.1.0 or 1.1.1.
- Confirm whether GRPCWebToHTTP2ServerCodec is reachable in deployed service paths.
- Map exposed gRPC-Web endpoints to public, partner, or internal access boundaries.
- Verify remediation against the GitHub advisory and release history.
- Review logs for denial-of-service symptoms around malformed request handling.
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.
CVE-2021-36153 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35267CVE reference · x_refsource_MISC
- https://github.com/grpc/grpc-swift/releasesCVE reference · x_refsource_MISC
- https://github.com/grpc/grpc-swift/security/advisories/GHSA-2jx2-qcm4-rf9hCVE reference · x_refsource_MISC
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.