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punchin-email CVE-2026-54649

| EUVDEUVD-2026-82386 LOW
Information Exposure (CWE-200)
2026-09-17 security-advisories@github.com
2.1
CVSS 4.0 · Vendor: github

Severity by source

Vendor (github) PRIMARY
2.1 LOW
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
4.3 MEDIUM

Confidentiality-only leak of the operator's own address, triggered by the operator's own reply (UI:R); no integrity or availability impact and no attacker privileges needed.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
4.0 AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
A
Scope
X

Lifecycle Timeline

5
Patch available
Sep 17, 2026 - 20:20 EUVD
Metadata Corrected
Sep 17, 2026 - 19:40 vuln.today
tag: Cloudflare added
Metadata Corrected
Sep 17, 2026 - 19:40 vuln.today
tag: Authentication Bypass removed
Metadata Corrected
Sep 17, 2026 - 19:40 vuln.today
tag: RCE removed
Analysis Generated
Sep 17, 2026 - 19:39 vuln.today

DescriptionCVE.org

punchin-email is a Cloudflare Email Worker that provides two-way role aliases while relaying mail to a private inbox. Prior to 1.5.0, handleInbound delivers inbound alias mail with message.forward(), which silently drops the added Reply-To header intended to route responses through the relay. When a correspondent sends mail to an alias and the operator replies, the mail client can send directly to the correspondent from the private FORWARD_TO inbox address, exposing that address. The disclosure is limited to the operator's own email address and does not expose third-party data or provide code execution or authentication bypass. This issue is fixed in version 1.5.0.

AnalysisAI

Information disclosure in punchin-email prior to 1.5.0 leaks the operator's private inbound inbox address (the FORWARD_TO value) to any correspondent who receives a reply from the alias. The Cloudflare Email Worker's handleInbound path used message.forward(), which silently strips the added Reply-To header, so when the operator hits Reply their mail client sends directly from the secret forwarding address instead of re-entering the relay; the issue is fixed in 1.5.0. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Exploit
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Execution
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Impact
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Vulnerability AssessmentAI

Exploitation Requires the punchin-email Cloudflare Email Worker running a version prior to 1.5.0 where handleInbound uses message.forward() (which drops the added Reply-To) instead of rewriting and re-sending the raw message. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuinely low-priority issue and the signals are internally consistent. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patch: upgrade to punchin-email 1.5.0 (release tag v1.5.0; fix commit 593685ffc0b8eb3949a4838e7bfe1e97b953d084, pull request 66) per the GitHub advisory GHSA-2ph7-69xm-hmwv - the release replaces the handleInbound message.forward() call with a raw-message rewrite plus send via EMAIL_SENDING so the alias is used as From and relay+<id>@RELAY_DOMAIN as Reply-To, fully closing the leak path. … Detailed patch versions, workarounds, and compensating controls in full report.

Threat intelligence, references, and detailed analysis are available after sign-in.

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CVE-2026-54649 vulnerability details – vuln.today

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