CVE
soapbar: verify_envelope_bsp accepts an unauthenticated embedded certificate (signature forgery / authentication bypass)
soapbar versions before 0.13.0 that expose verify_envelope_bsp are affected when callers trust its result without CA-chain validation, allowlists, or pinning. Fixed in 0.13.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 0.13.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.13.0.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The soapbar SOAP library's BSP signature check trusts a certificate embedded in the message itself, so an attacker can forge a signed message that passes as coming from a trusted party. Remotely, without logging in and without any user action, an attacker can sign a forged envelope with their own certificate and bypass authentication in systems that rely on that check.
Read the original 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.
Who should check
Teams running soapbar before 0.13.0 that call verify_envelope_bsp() to authenticate SOAP/WS-Security senders
Read the source excerpt
“soapbar < 0.13.0 (all published versions exposing verify_envelope_bsp )”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.2/10CVSS 8.2
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 30 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.13.0.
Workaround: Do not treat a successful verify_envelope_bsp() as authentication.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-64855 (soapbar: verify_envelope_bsp accepts an unauthenticated embedded certificate (signature forgery / authentication bypass)), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-64855 (entry last updated 2026-11-11):
Affected:
- hitoshyamamoto soapbar: fixed in 0.13.0
Fixed versions: 0.13.0.
Conditions (all must be true for the bug to be hit):
- soapbar versions before 0.13.0 that expose verify_envelope_bsp (source: https://github.com/hitoshyamamoto/soapbar/security/advisories/GHSA-859w-52fx-hcm6)
- Caller relies on verify_envelope_bsp without CA-chain validation, issuer/subject allowlist, or pinning (source: https://github.com/hitoshyamamoto/soapbar/security/advisories/GHSA-859w-52fx-hcm6)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
Workaround: Do not treat a successful verify_envelope_bsp() as authentication. (source: https://github.com/hitoshyamamoto/soapbar/security/advisories/GHSA-859w-52fx-hcm6)
CISA KEV: CVE-2026-64855 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-64855 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/hitoshyamamoto/soapbar/security/advisories/GHSA-859w-52fx-hcm6
- https://github.com/hitoshyamamoto/soapbar/pull/71
- https://github.com/hitoshyamamoto/soapbar/releases/tag/v0.13.0
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-64855
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-64855"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- hitoshyamamoto soapbar
fixed in 0.13.0
Evidence 5
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 2
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-64855
Is CVE-2026-64855 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
verify_envelope_bsp accepts the certificate embedded in a signed envelope without checking it against a trusted CA chain. An attacker can forge a signed envelope with their own embedded certificate, pass verification, and impersonate the signer.Source: github.com
Which versions are affected by CVE-2026-64855?
soapbar: before 0.13.0.Source: cve.now feed data
Am I affected, and how do I check?
soapbar versions before 0.13.0 that expose verify_envelope_bsp are affected. The risk applies where callers rely on it without CA-chain validation, an issuer/subject allowlist, or pinning. Check the installed soapbar version and whether any code calls verify_envelope_bsp.Source: github.com
How do I fix CVE-2026-64855?
Upgrade soapbar to 0.13.0, which contains the fix. Until the upgrade is done, do not treat a successful verify_envelope_bsp() call as authentication.Source: github.com