CVE-2023-49087 is a medium-severity (CVSS 6.8) CWE-345 vulnerability in simplesamlphp/xml-security. 1 public exploit reference exists, so weaponization risk is real. A fix is available for simplesamlphp/xml-security — see the affected versions and patch details below.
Validation of SignedInfo
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-49087 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
simplesamlphp/xml-security🐘simplesamlphp/saml2Real-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
xml-security is a library that implements XML signatures and encryption. Validation of an XML signature requires verification that the hash value of the related XML-document matches a specific DigestValue-value, but also that the cryptographic signature on the SignedInfo-tree (the one that contains the DigestValue) verifies and matches a trusted public key. If an attacker somehow (i.e. by exploiting a bug in PHP's canonicalization function) manages to manipulate the canonicalized version's DigestValue, it would be possible to forge the signature. This issue has been patched in version 1.6.12 and 5.0.0-alpha.13.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | simplesamlphp/xml-security | ≥ 1.6.11&&< 1.6.12 | 1.6.12composer require simplesamlphp/xml-security:^1.6.12 |
| 🐘Packagist | simplesamlphp/saml2 | ≥ 5.0.0-alpha.12&&< 5.0.0-alpha.13 | 5.0.0-alpha.13composer require simplesamlphp/saml2:^5.0.0-alpha.13 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for simplesamlphp/xml-security, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update simplesamlphp/xml-security to 1.6.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-49087 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-49087 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-49087. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-49087 in your dependencies?
O3 Security finds CVE-2023-49087 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.