CVE-2026-1664

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Source
https://cve.org/CVERecord?id=CVE-2026-1664
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-1664.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-1664
Aliases
Published
2026-02-03T11:39:18.810Z
Modified
2026-07-15T01:48:53.564112424Z
Severity
  • 6.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N CVSS Calculator
Summary
Insecure Direct Object Reference (IDOR) via Header-Based Email Routing
Details

Summary

An Insecure Direct Object Reference has been found to exist in createHeaderBasedEmailResolver() function within the Cloudflare Agents SDK. The issue occurs because the Message-ID and References headers are parsed to derive the target agentName and agentId without proper validation or origin checks, allowing an external attacker with control of these headers to route inbound mail to arbitrary Durable Object instances and namespaces .

Root cause

The createHeaderBasedEmailResolver() function lacks cryptographic verification or origin validation for the headers used in the routing logic, effectively allowing external input to dictate internal object routing.

Impact

Insecure Direct Object Reference (IDOR) in email routing lets an attacker steer inbound mail to arbitrary Agent instances via spoofed Message-ID.

Mitigation:

  • PR: https://github.com/cloudflare/agents/blob/main/docs/email.md ] provides the necessary architectural context for coding agents to mitigate the issue by refactoring the resolver to enforce strict identity boundaries.
  • Agents-sdk users should upgrade to agents@0.3.7
Database specific 
{
    "cwe_ids": [
        "CWE-639"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/1xxx/CVE-2026-1664.json",
    "cna_assigner": "cloudflare"
}
References

Affected packages

Git / github.com/cloudflare/agents

Affected ranges

Type
GIT
Repo
https://github.com/cloudflare/agents
Events
Introduced
f6c26e41e831ab9735f06f47d761ad7c231ae747
Last affected
38243855f12b4d430ed6ea20e49384bd1d6af65d
Database specific 
{
    "extracted_events": [
        {
            "introduced": "0.0.104"
        },
        {
            "last_affected": "0.3.6"
        }
    ],
    "source": "AFFECTED_FIELD"
}

Affected versions

@cloudflare/ai-chat@0.*
@cloudflare/ai-chat@0.0.3
@cloudflare/ai-chat@0.0.4
@cloudflare/codemode@0.*
@cloudflare/codemode@0.0.3
@cloudflare/codemode@0.0.4
@cloudflare/codemode@0.0.5
agents@0.*
agents@0.0.104
agents@0.0.105
agents@0.0.106
agents@0.0.107
agents@0.0.108
agents@0.0.109
agents@0.1.1
agents@0.1.2
agents@0.1.3
agents@0.1.4
agents@0.1.5
agents@0.1.6
agents@0.2.0
agents@0.2.1
agents@0.2.10
agents@0.2.11
agents@0.2.12
agents@0.2.13
agents@0.2.14
agents@0.2.15
agents@0.2.16
agents@0.2.17
agents@0.2.18
agents@0.2.19
agents@0.2.2
agents@0.2.20
agents@0.2.21
agents@0.2.22
agents@0.2.23
agents@0.2.24
agents@0.2.25
agents@0.2.26
agents@0.2.27
agents@0.2.28
agents@0.2.29
agents@0.2.3
agents@0.2.30
agents@0.2.31
agents@0.2.32
agents@0.2.34
agents@0.2.35
agents@0.2.4
agents@0.2.6
agents@0.2.7
agents@0.2.8
agents@0.2.9
agents@0.3.0
agents@0.3.1
agents@0.3.3
agents@0.3.4
agents@0.3.5
agents@0.3.6
hono-agents@0.*
hono-agents@0.0.94
hono-agents@0.0.95
hono-agents@0.0.96
hono-agents@0.0.97
hono-agents@0.0.98
hono-agents@0.0.99
hono-agents@1.*
hono-agents@1.0.1
hono-agents@1.0.2
hono-agents@2.*
hono-agents@2.0.0
hono-agents@2.0.1
hono-agents@2.0.2
hono-agents@2.0.3
hono-agents@2.0.4
hono-agents@2.0.5
hono-agents@2.0.6
hono-agents@2.0.7
hono-agents@2.0.8
hono-agents@3.*
hono-agents@3.0.0
hono-agents@3.0.1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-1664.json"