CVE-2026-18089

Published Aug 3, 2026

Last updated a month ago

CVSS high 7.5

Overview

Description
Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass by verifying responses against the response-embedded certificate in verify_xml when no trust anchor is configured. verify_xml in Net::SAML2::Role::VerifyXML runs "return if !$anchors && !$cacert;" as soon as the XML::Sig check succeeds, and that check uses the X.509 certificate taken from the response's own dsig:KeyInfo/dsig:X509Certificate element, so an unanchored response is checked only against the key it carries. Binding::POST declares cacert as an optional Maybe[Str] with no default, so a POST binding built without one takes that path, and _verify_encrypted_assertion returns early the same way with "return $xml unless $cacert;". Any caller that constructs Binding::POST or calls Assertion->new_from_xml without a cacert, cert_text, or anchors argument accepts a response signed by an attacker generated key whose self-signed certificate is embedded in that response, authenticating an arbitrary assertion.
Source
9b29abf9-4ab0-4765-b253-1875cd9b441e
NVD status
Analyzed
Products
net\

Risk scores

CVSS 3.1

Type
Secondary
Base score
7.5
Impact score
3.6
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Severity
HIGH

Weaknesses

9b29abf9-4ab0-4765-b253-1875cd9b441e
CWE-295

Social media

Hype score
Not currently trending

Configurations

Related CVEs

  1. Net::SAML2 versions before 0.86 for Perl allow authentication bypass because _verify_encrypted_assertion accepts an EncryptedAssertion whose decrypted content carries no signature. _verify_encrypted_assertion decrypts the EncryptedAssertion and returns it as verified when it carries no signature, via "return $xml unless $xpath->exists('dsig:Signature', $assert);". The signature check and the trust anchor check that follow run only when a signature is present, so a decrypted assertion with no dsig:Signature element reaches new_from_xml unverified and its NameID and attributes are read into the assertion object. An SP's encryption certificate is published in its SAML metadata so the IdP can encrypt to it, so any party can encrypt an unsigned assertion to that certificate, wrap it in a samlp:Response, and post it to the assertion consumer service. Any caller that configures a decryption key_file, and so accepts EncryptedAssertions, takes identity fields from an assertion that no trust anchor covers, and an unauthenticated party can authenticate as an arbitrary user. Callers with no key_file configured do not decrypt and are unaffected.•CVE-2026-18108
  2. Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass via XML signature wrapping because new_from_xml reads assertion identity with document-wide XPath instead of the signed subtree. new_from_xml reads the NameID, attribute values, SessionIndex, audience and other identity fields with document-wide XPath, such as //saml:Assertion/saml:AttributeStatement/saml:Attribute and //saml:Subject/saml:NameID, which select the first matching element in document order rather than the element covered by the verified signature. handle_response confirms that a signature is present and, when a cacert is configured, that it chains to the CA, but XML::Sig verifies only the element named by the signature's Reference URI, so unsigned sibling assertions in the same document are not covered. An attacker who holds any one IdP-signed assertion can add an unsigned attacker-authored assertion earlier in document order; the signature still verifies and the document-order XPath returns the attacker's NameID and attributes. Any caller that passes an untrusted Response to new_from_xml can accept identity fields from an assertion the IdP never signed, even when a cacert trust anchor is configured, so a party holding one valid IdP-signed assertion can authenticate as an arbitrary user.•CVE-2026-18092
  3. Net::CIDR::Set versions through 0.20 for Perl did not validate network masks. The mask portion of a network mask could contain Unicode digits such as the Arabic-Indic One (U+0661), or non-digits, which were ignored. This could allow network masks to accept larger networks. Leading zeros were also accepted, but treated as decimal instead of octal. This could lead to confusion about what networks are acceptable.•CVE-2026-49942
  4. Net::CIDR::Set versions through 0.20 for Perl did not validate IP addresses. The add method called the _encode method to parse addresses. If the addresses did not look like netmasks or network ranges, then they were assumed to single IP addresses and passed back to itself as a 32-bit or 128-bit netmask. If the argument was not a well-formed IP address, then this would lead to indefinite recursion. An attacker could use this to cause a denial of service.•CVE-2026-49941
  5. Net::CIDR::Set versions through 0.20 for Perl accept non-ASCII IP addresses and netmasks. Unicode digits such as the Arabic-Indic One (U+0661) were accepted but not properly parsed as numbers. This could allow network masks to accept larger networks.•CVE-2026-49940

References

Sources include official advisories and independent security research.