CVE-2021-27098
HIGHCVE-2021-27098 is a high-severity (CVSS 8.1) CWE-295 vulnerability in github.com/spiffe/spire. O3 Security confirms whether CVE-2021-27098 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Legacy Node API Allows Impersonation in github.com/spiffe/spire/pkg/server/endpoints/node
Real-World Exposure
github.com/spiffe/spire🐹github.com/spiffe/spire🐹github.com/spiffe/spire🐹github.com/spiffe/spire🐹github.com/spiffe/spireReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
In SPIRE 0.8.1 through 0.8.4 and before versions 0.9.4, 0.10.2, 0.11.3 and 0.12.1, specially crafted requests to the FetchX509SVID RPC of SPIRE Server’s Legacy Node API can result in the possible issuance of an X.509 certificate with a URI SAN for a SPIFFE ID that the agent is not authorized to distribute. Proper controls are in place to require that the caller presents a valid agent certificate that is already authorized to issue at least one SPIFFE ID, and the requested SPIFFE ID belongs to the same trust domain, prior to being able to trigger this vulnerability. This issue has been fixed in SPIRE versions 0.8.5, 0.9.4, 0.10.2, 0.11.3 and 0.12.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/spiffe/spire | ≥ 0.8.1&&< 0.8.5 | 0.8.5 |
| 🐹Go | github.com/spiffe/spire | ≥ 0.9.0&&< 0.9.4 | 0.9.4 |
| 🐹Go | github.com/spiffe/spire | ≥ 0.10.0&&< 0.10.2 | 0.10.2 |
| 🐹Go | github.com/spiffe/spire | ≥ 0.11.0&&< 0.11.3 | 0.11.3 |
| 🐹Go | github.com/spiffe/spire | ≥ 0.12.0&&< 0.12.1 | 0.12.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/spiffe/spire. 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 github.com/spiffe/spire to 0.8.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-27098 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-2021-27098 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-2021-27098. 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-2021-27098 in your dependencies?
O3 detects CVE-2021-27098 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.