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CVE-2026-64855

HIGHCVSS 8.2/10EPSS 0.19%

Last modified

CVE-2026-64855 is a high-severity vulnerability rated 8.2/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
8.2/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

EPSS Probability
0.19%

8.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
hitoshyamamotosoapbar< 0.13.0

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-64855?
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.
How severe is CVE-2026-64855?
CVE-2026-64855 has a CVSS score of 8.2/10 (HIGH severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.
How do I fix CVE-2026-64855?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST