How severe is CVE-2021-27098?

CVE-2021-27098 has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-27098?

CVE-2021-27098 affects the following packages: github.com/spiffe/spire (Go), github.com/spiffe/spire (Go), github.com/spiffe/spire (Go), github.com/spiffe/spire (Go), github.com/spiffe/spire (Go). Ecosystems affected: Go.

How do I fix CVE-2021-27098?

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.

How do I detect CVE-2021-27098 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/spiffe/spire, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-27098 if there is no patch (or I can't update yet)?

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.

Is CVE-2021-27098 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-27098 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-27098?

CVE-2021-27098 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 45th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-27098?

CVE-2021-27098 is classified as CWE-295 (CWE-295). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-27098 published, and has it been updated?

CVE-2021-27098 was published on March 5, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2021-27098 — spire

HIGHFix: spiffe/spire@3c5115b

CVE-2021-27098 is a high-severity (CVSS 8.1) CWE-295 vulnerability in github.com/spiffe/spire. A fix is available for github.com/spiffe/spire — see the affected versions and patch details below.

Legacy Node API Allows Impersonation in github.com/spiffe/spire/pkg/server/endpoints/node

Also known asGHSA-h746-rm5q-8mgq

Published

Mar 5, 2021

Updated

Jul 9, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs45th percentile — riskier than 45% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-27098 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

5 pkgs affected

🐹github.com/spiffe/spire🐹github.com/spiffe/spire🐹github.com/spiffe/spire🐹github.com/spiffe/spire🐹github.com/spiffe/spire

Real-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

Summary

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 (github.com/spiffe/spire/pkg/server/endpoints/node) 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.

What are the changes introduced by the patched versions?

The changes introduced to address this issue are related to enforcing that the FetchX509SVID RPC of SPIRE Server’s Legacy Node API only issues X.509 certificates with SPIFFE IDs that the agent is authorized to distribute.

The patched version also includes a back-ported change that improves the handling of file descriptors related to workload attestation in SPIRE Agent.

There are no changes in the expected behavior of SPIRE.

Should I upgrade SPIRE?

All SPIRE users running affected versions are advised to upgrade to the corresponding patched version.

Workarounds

No workarounds have been identified for this vulnerability.

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/spiffe/spire`	≥ 0.8.1&&< 0.8.5	0.8.5`go get github.com/spiffe/spire@v0.8.5`
🐹Go	`github.com/spiffe/spire`	≥ 0.9.0&&< 0.9.4	0.9.4`go get github.com/spiffe/spire@v0.9.4`
🐹Go	`github.com/spiffe/spire`	≥ 0.10.0&&< 0.10.2	0.10.2`go get github.com/spiffe/spire@v0.10.2`
🐹Go	`github.com/spiffe/spire`	≥ 0.11.0&&< 0.11.3	0.11.3`go get github.com/spiffe/spire@v0.11.3`
🐹Go	`github.com/spiffe/spire`	≥ 0.12.0&&< 0.12.1	0.12.1`go get github.com/spiffe/spire@v0.12.1`

Affected Products

1 product · 5 configurations

Application

spirecncf

≥ 0.12.0 && ≤ 0.8.4

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/spiffe/spire, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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.

Frequently Asked Questions

#### Summary 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 (github.com/spiffe/spire/pkg/server/endpoints/node) 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