CVE-2026-22772 is a medium-severity (CVSS 5.8) Server-Side Request Forgery (SSRF) vulnerability in github.com/sigstore/fulcio. A fix is available for github.com/sigstore/fulcio — see the affected versions and patch details below.
Fulcio vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-22772.
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-2026-22772 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 377,166 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
github.com/sigstore/fulcioReal-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
Fulcio is a certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.5, Fulcio's metaRegex() function uses unanchored regex, allowing attackers to bypass MetaIssuer URL validation and trigger SSRF to arbitrary internal services. Since the SSRF only can trigger GET requests, the request cannot mutate state. The response from the GET request is not returned to the caller so data exfiltration is not possible. A malicious actor could attempt to probe an internal network through Blind SSRF. This vulnerability is fixed in 1.8.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/sigstore/fulcio | all versions | 1.8.5go get github.com/sigstore/fulcio@v1.8.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/fulcio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/sigstore/fulcio to 1.8.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22772 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-2026-22772 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-22772. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated Moderate for Red Hat products. A flaw in Fulcio's URL validation allows attackers to bypass security checks, leading to Server-Side Request Forgery (SSRF). This could enable internal network reconnaissance within affected Red Hat OpenShift and Ansible Automation Platform deployments, though…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Openshift Data Foundation 4.22 | odf4/cephcsi-rhel9:1782932114 | RHSA-2026:37387 |
| Red Hat Trusted Artifact Signer 1.2 | rhtas/cosign-rhel9:1770733887 | RHSA-2026:2922 |
| Red Hat Trusted Artifact Signer 1.2 | rhtas/client-server-rhel9:1770789792 | RHSA-2026:2924 |
| Red Hat Trusted Artifact Signer 1.3 | rhtas/cosign-rhel9:1770107585 | RHSA-2026:2136 |
| Red Hat Trusted Artifact Signer 1.3 | rhtas/fulcio-rhel9:1770107446 | RHSA-2026:2144 |
Frequently Asked Questions
Is CVE-2026-22772 in your dependencies?
O3 Security finds CVE-2026-22772 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.