SimpleSAMLphp SAML2 has an XXE in parsing SAML messagesGHSA-pxm4-r5ph-q2m2
HIGHFix: simplesamlphp/saml2@5fd4ce4GHSA-pxm4-r5ph-q2m2 is a high-severity (CVSS 8.3) XML External Entity (XXE) vulnerability in simplesamlphp/saml2. A fix is available for simplesamlphp/saml2 — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-pxm4-r5ph-q2m2.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
simplesamlphp/saml2🐘simplesamlphp/saml2-legacyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
When loading an (untrusted) XML document, for example the SAMLResponse, it's possible to induce an XXE.
$options is defined as: https://github.com/simplesamlphp/saml2/blob/717c0adc4877ebd58428637e5626345e59fa0109/src/SAML2/DOMDocumentFactory.php#L41 including the DTDLoad option, which allows an attacker to read file contents from local file system OR internal network.
While there is the NONET option, an attacker can simply bypass if by using PHP filters: php://filter/convert.base64-encode/resource=http://URL OR FILE
From there an attacker can induce network connections and steal the targeted file OOB (haven't fully tested this).
RCE may be possible with the php://expect or php://phar wrappers, but this hasn't been tested.
Note: The mitigation here: https://github.com/simplesamlphp/saml2/blob/717c0adc4877ebd58428637e5626345e59fa0109/src/SAML2/DOMDocumentFactory.php#L63-L69 Comes too late, as the XML has already been loaded into a document. Mitigation:
Remove the LIBXML_DTDLOAD | LIBXML_DTDATTR options. Additionally, as a defense in depth measure, check if there is the string: <!DOCTYPE inside the XML before parsing it. (This is not a complete fix because someone may be able to exploit some parser differentials, to load a DOCTYPE, maybe through spacing like: <! DOCTYPE)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | simplesamlphp/saml2 | all versions | 4.6.14composer require simplesamlphp/saml2:^4.6.14 |
| 🐘Packagist | simplesamlphp/saml2-legacy | all versions | 4.6.14composer require simplesamlphp/saml2-legacy:^4.6.14 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for simplesamlphp/saml2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update simplesamlphp/saml2 to 4.6.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pxm4-r5ph-q2m2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is GHSA-pxm4-r5ph-q2m2 in your dependencies?
Find it across Packagist, including transitive dependencies.