GHSA-f4r5-q63f-gcww
MEDIUMKeylime registrar and (untrusted) Agent can be bypassed by an attacker
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.
Blast Radius
keylimeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
A security issue was found in the Keylime registrar code which allows an attacker to effectively bypass the challenge-response protocol used to verify that an agent has indeed access to an AIK which in indeed related to the EK.
When an agent starts up, it will contact a registrar and provide a public EK and public AIK, in addition to the EK Certificate. This registrar will then challenge the agent to decrypt a challenge encrypted with the EK.
When receiving the wrong "auth_tag" back from the agent during activation, the registrar answers with an error message that contains the expected correct "auth_tag" (an HMAC which is calculated within the registrar for checking). An attacker could simply record the correct expected "auth_tag" from the HTTP error message and perform the activate call again with the correct expected "auth_tag" for the agent.
The security issue allows an attacker to pass the challenge-response protocol during registration with (almost) arbitrary registration data. In particular, the attacker can provide a valid EK Certificate and EK, which passes verification by the tenant (or registrar), while using a compromised AIK, which is stored unprotected outside the TPM and is unrelated to former two. The attacker then deliberately fails the initial activation call to get to know the correct "auth_tag" and then provides it in a subsequent activation call. This results in an agent which is (incorrectly) registered with a valid EK Certificate, but with a compromised/unrelated AIK.
Patches
Users should upgrade to release 7.5.0
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | keylime | all versions | 7.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for keylime. 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 keylime to 7.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f4r5-q63f-gcww 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 GHSA-f4r5-q63f-gcww 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 GHSA-f4r5-q63f-gcww. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-f4r5-q63f-gcww in your dependencies?
O3 detects GHSA-f4r5-q63f-gcww across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.