CVE-2026-49454 is a critical-severity (CVSS 9.1) Improper Authentication vulnerability in relyra. O3 Security confirms whether CVE-2026-49454 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Relyra SAML SignatureValue not cryptographically verified -> authentication bypass
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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 CVE-2026-49454.
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-2026-49454 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 369,023 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
relyraReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
Relyra is a strict-by-default SAML 2.0 Service Provider library for Elixir and Phoenix. Versions 1.0.0 and 1.1.0 accept forged SAML signatures because SignatureValue was not cryptographically verified before the library returned a successful authentication result. The XMLDSig trust boundary was incomplete as :public_key.verify over the exclusive-C14N canonicalized SignedInfo was not performed against the configured IdP certificate's public key, DigestValue was not recomputed over the canonicalized referenced element, and canonicalize/2 remained an unused passthrough in the signature-verification path. The result was a structure-only acceptance path where document shape and trust-source rejection could succeed without proving the signature bytes. A forged SignatureValue carrying an attacker-controlled NameID could be accepted as {:ok}. This issue has been fixed in version 1.2.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | relyra | ≥ 1.0.0&&< 1.2.0 | 1.2.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for relyra. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update relyra to 1.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49454 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 pinpoints whether CVE-2026-49454 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-49454. 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-2026-49454 in your dependencies?
O3 detects CVE-2026-49454 across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.