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AgenticMail: Unauthenticated inbound mail triggers bypassPermissions resume of the operator's Claude Code session (bridge-wake)

High severity GitHub Reviewed Published Jun 18, 2026 in agenticmail/agenticmail • Updated Jul 21, 2026

Package

npm @agenticmail/claudecode (npm)

Affected versions

< 0.2.39

Patched versions

0.2.39
npm @agenticmail/codex (npm)
< 0.1.33
0.1.33
npm @agenticmail/core (npm)
< 0.9.43
0.9.43
npm @agenticmail/openclaw (npm)
< 0.5.71
0.5.71

Description

Summary

Two inbound-mail handlers act on a privileged effect without verifying that the sender is the operator, while a sibling handler in the same repo does. The higher-impact one: any external email routed to the bridge inbox causes the dispatcher to resume the operator's Claude Code session with permissionMode: 'bypassPermissions', embedding the attacker-controlled from/subject/preview verbatim into the prompt the resumed agent reads — an indirect prompt injection into a fully-privileged agent (Bash/Write/Edit/WebFetch + the agenticmail MCP toolbelt) running as the operator's OAuth identity. The sibling operator-query email-reply hook gates the same untrusted-From provenance with isOperatorReplySender(replyFrom, config.operatorEmail) (fail-closed); the bridge-wake path — a strictly higher-privilege effect — has no equivalent.

Affected code (current HEAD, commit b95f52e)

Untrusted provenance: external inbound email enters at packages/api/src/routes/inbound.ts:41 (POST /mail/inbound); the x-inbound-secret authenticates only the relay->API hop, not the external sender, so from/subject/preview are attacker-controlled.

Privileged sink (bridge-wake, bypassPermissions):

  • packages/claudecode/src/dispatcher.ts:2040 handleBridgeMail extracts subject/from/preview (:2045-2049) and calls planBridgeWake({ session, mail: { ..., from, preview } }) (:2052) with NO sender check — routing keys only on session freshness (skip-live / escalate / resume).
  • planBridgeWake -> packages/core/src/host-bridge.ts:141 composeBridgeWakePrompt embeds the untrusted from/subject/preview (preview sliced to 600 chars at :144) verbatim into the prompt.
  • packages/claudecode/src/bridge-wake.ts:103 resumeBridgeSession runs the prompt via the Claude Code SDK with permissionMode: 'bypassPermissions' against the operator's last session (resume + same mcpServers).

Guarded sibling (same class, authenticated): packages/api/src/routes/inbound.ts:102 rejects an operator-query email reply unless isOperatorReplySender(replyFrom, config.operatorEmail) (def packages/core/src/phone/realtime-tools.ts:999, fail-closed when no operatorEmail), with a v0.9.53 security-review comment (inbound.ts:93-100) stating inbound mail provenance is untrusted and an emailed answer is only honored when its From matches the configured operator. The Telegram sibling likewise gates on operatorChatId. The bridge-wake path ignores this exact lesson.

Secondary instance (same root cause): packages/core/src/gateway/manager.ts:261 tryProcessApprovalReply releases a held outbound email on an "approve" reply matched only by In-Reply-To / notification_message_id, with no sender check — again unlike the isOperatorReplySender sibling.

Impact

In a configured headless-bridge deployment (operator uses the CLI so a host-session is saved; session fresh <24h per host-sessions.ts:127; external mail routed to the bridge inbox via relay sub-addressing or a Cloudflare webhook), an external sender achieves indirect prompt injection into a bypassPermissions operator session -> arbitrary OS command execution, filesystem read/write, and exfiltration under the operator's OAuth identity. The auth gap (no sender check on the bridge path) is structural and unconditional; the impact realization is config-conditional and depends on the resumed model following injected instructions.

Proof of concept (static / request-difference; dynamic on operator's OWN setup only)

Static: the from/subject/preview extracted at dispatcher.ts:2045-2049 flow into composeBridgeWakePrompt (host-bridge.ts:141) and resumeBridgeSession (bridge-wake.ts:103) with no interposed sender check, while the sibling inbound.ts:102 has one — the same untrusted-From provenance is authenticated on one privileged email path and not on the higher-privileged one. Dynamic (own instance only): with a configured bridge + fresh host-session, send mail from a non-operator address into the bridge inbox whose subject/preview contains a benign instruction writing a fresh CSPRNG marker; observe the resumed bypassPermissions session act on it. Use only your own instance; do not target third-party deployments.

Suggested fix

Mirror the guarded sibling: before any bypassPermissions resume (dispatcher.ts handleBridgeMail, before planBridgeWake), require trusted provenance — an internal sub-agent wake OR isOperatorReplySender(from, config.operatorEmail); otherwise deliver the mail normally but do NOT resume. Reuse the existing exported isOperatorReplySender from @agenticmail/core so the two privileged email paths share one authentication helper. Defense-in-depth: in composeBridgeWakePrompt, wrap the untrusted fields in explicit untrusted-data delimiters and drop bypassPermissions for mail-triggered resumes whose provenance is not the operator. Apply the same sender gate to tryProcessApprovalReply (manager.ts:261).

Affected versions

Present on current HEAD (core 0.9.42 / claudecode 0.2.38, commit b95f52e). No fix retrofits the sender check onto bridge-wake.

Severity (honest, both ways)

HIGH, plausibly CRITICAL in a configured headless-bridge deployment. Ceiling ~9.0 (unauthenticated external sender -> operator-privileged code execution). Floor ~7.0: the auth gap is unconditional, but full impact requires (1) a fresh <24h host-session, (2) external mail routed to the bridge inbox, (3) the resumed model obeying injected instructions (non-deterministic). Not a deterministic RCE primitive. CWE-306 (missing authentication for the privileged action) + CWE-77/CWE-94 (injected instructions realized as command execution). Novelty: the two existing agenticmail advisories (CVE-2026-50287 MCP missing-auth; CVE-2026-47255 storage SQL) do not cover this sink. Please rate per your deployment assumptions.

References

@ope-olatunji ope-olatunji published to agenticmail/agenticmail Jun 18, 2026
Published to the GitHub Advisory Database Jun 18, 2026
Reviewed Jun 18, 2026
Published by the National Vulnerability Database Jul 20, 2026
Last updated Jul 21, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity High
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(20th percentile)

Weaknesses

Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. Learn more on MITRE.

CVE ID

CVE-2026-57495

GHSA ID

GHSA-fq4x-789w-jg5h

Source code

Credits

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