# CVE-2026-64855: soapbar: verify_envelope_bsp accepts an unauthenticated embedded certificate (signature forgery / authentication bypass)

Status: published. Published: 2026-11-11. Updated: 2026-11-11.

soapbar is a SOAP library for Python — client, server, and WSDL handling. Prior to version 0.13.0, verify_envelope_bsp() derived its trust anchor from the message it was verifying. It read the X.509 certificate out of the caller-untrusted wsse:BinarySecurityToken, validated only that certificate's not-before / not-after dates, and then verified the signature against that same certificate. There was no CA-chain validation, no issuer/subject allowlist, and no pinning. A successful verify_envelope_bsp() therefore proved only that the envelope was signed by whoever supplied the embedded certificate — never that it was signed by a trusted party. An attacker who mints their own certificate, signs a forged envelope, and embeds that certificate in the token passes verification. Any consumer that treats a successful BSP verification as authentication can be impersonated (signature forgery / authentication bypass). verify_envelope() (which pins a caller-supplied x509_cert) was not affected — the flaw was specific to the BSP variant whose trust anchor came from the message. This issue has been patched in version 0.13.0.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- hitoshyamamoto / soapbar: < 0.13.0 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N; source: CNA: GitHub_M

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-295, CWE-347

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/hitoshyamamoto/soapbar/security/advisories/GHSA-859w-52fx-hcm6 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/hitoshyamamoto/soapbar/pull/71 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/hitoshyamamoto/soapbar/releases/tag/v0.13.0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/hitoshyamamoto/soapbar/pull/71 (security-advisories@github.com)

- https://github.com/hitoshyamamoto/soapbar/releases/tag/v0.13.0 (security-advisories@github.com)

- https://github.com/hitoshyamamoto/soapbar/security/advisories/GHSA-859w-52fx-hcm6 (security-advisories@github.com)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-64855; retrieved 2026-11-11; source updated 2026-11-11

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64855; retrieved 2026-11-11; source updated 2026-11-11

Revision: d03f77380cef79acf32821fe67a31c48202ef91e9b8501caf91c0717b66af1bd

Canonical: https://y2.dev/cve/CVE-2026-64855

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