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CVE-2026-108716 punkpeye CVE debrief

CVE-2026-108716: The mcp-remote package, versions 0.8.0 through 0.14.3, contains a cleartext transmission vulnerability in the authorizeWithDeviceCode function. This function sends client secrets and receives tokens without enforcing HTTPS endpoints, allowing on-path network attackers to capture sensitive information when device authorization and token endpoints are non-loopback http URLs. Defenders responsible for mcp-remote deployments should assess exposure and prioritize verification of HTTPS usage and client secret handling.

Vendor
punkpeye
Product
mcp-remote
CVSS
MEDIUM 6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-11
Original CVE updated
2026-10-11
Advisory published
2026-10-11
Advisory updated
2026-10-11

Who should care

Defenders responsible for mcp-remote deployments, particularly those using device authorization and token endpoints over non-loopback http URLs, should assess exposure and prioritize verification of HTTPS usage and client secret handling.

Why it matters

CVE-2026-108716 allows on-path network attackers to capture client secrets and issued access and refresh tokens in mcp-remote 0.8.0 through 0.14.3. Defenders should verify HTTPS usage, review client secret handling, and ensure network protections are in place.

  • Verify HTTPS usage for device authorization and token endpoints to prevent cleartext transmission.
  • Review client secret handling practices to minimize exposure.
  • Ensure network protections are in place to prevent on-path attacks.
  • Monitor for potential unauthorized access attempts.

Technical summary

The mcp-remote package, versions 0.8.0 through 0.14.3, contains a cleartext transmission vulnerability in the authorizeWithDeviceCode function. This function sends client secrets and receives tokens without enforcing HTTPS endpoints, allowing on-path network attackers to capture sensitive information. The vulnerability is particularly concerning when device authorization and token endpoints are non-loopback http URLs. Defenders should prioritize verifying the use of HTTPS for these endpoints, reviewing client secret handling, and ensuring network protections are in place to prevent such attacks.

Defensive priority

Defenders should prioritize verifying the use of HTTPS for device authorization and token endpoints, reviewing client secret handling, and ensuring network protections are in place.

Recommended defensive actions

  • Verify the use of HTTPS for device authorization and token endpoints in mcp-remote configurations.
  • Review and update client secret handling practices to minimize exposure.
  • Ensure network protections are in place to prevent on-path attacks.
  • Monitor for and respond to potential unauthorized access attempts.
  • Perform vulnerability scanning to identify exposed systems.
  • Implement additional logging and monitoring for suspicious activity.
  • Coordinate with vendors for patching or mitigation guidance.

Evidence notes

The CVE record and source item provide details on the cleartext transmission vulnerability in mcp-remote 0.8.0 through 0.14.3. The vulnerability allows on-path network attackers to capture client secrets and issued access and refresh tokens when device authorization and token endpoints are non-loopback http URLs.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-108716 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-108716

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-108716 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-108716

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • mcp-remote 0.8.0 through 0.14.3 Cleartext Credential Transmission via --device-code OAuth Grant

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/108xxx/CVE-2026-108716.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://hackmd.io/@haind03/punkpeye-mcp-remote-device-code-cleartext-oauth-transport

    Supplemental source - third-party-advisory

  • Source reference

    Unverified legacy reference

    URL: https://github.com/punkpeye/mcp-remote/blob/v0.14.3/src/lib/device-authorization.ts

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://github.com/punkpeye/mcp-remote/blob/v0.14.3/src/lib/client-credentials.ts

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://github.com/punkpeye/mcp-remote

    Supplemental source - product

  • Source reference

    Unverified legacy reference

    URL: https://www.vulncheck.com/advisories/mcp-remote-0.8.0-through-0.14.3-cleartext-credential-transmission-via-device-code-oauth-grant

    Supplemental source - third-party-advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.