CVE-2026-22772 Fulcio vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass
Attackers can bypass URL validation to trigger blind SSRF against internal services, enabling network probing without data exfiltration or state mutation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-22772?
CVE-2026-22772 is a medium-severity server-side request forgery vulnerability in sigstore fulcio, published on 12 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-918
Which versions are affected by CVE-2026-22772?
3 open source packages ship an affected version, including github.com/sigstore/fulcio. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/sigstore/fulcio Go | All versions | 1.8.5 |
github.com/sigstore/fulcio Go | All versions | 1.8.5 |
github.com/sigstore/fulcio Go | All versions | 1.8.5 |
Linux distribution packages (2)
hauler openSUSE:Leap 16.0 | All versions | 1.4.1-bp160.1.1 |
hauler openSUSE:Tumbleweed | All versions | 1.4.1-1.1 |
Products include Linuxfoundation Fulcio.
How do I fix CVE-2026-22772?
Upgrade github.com/sigstore/fulcio to 1.8.5 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-22772 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-22772 exists.
Other vulnerabilities in sigstore fulcio
Sources
Also known as CLEANSTART-2026-LN74162, CLEANSTART-2026-NY15561, DEBIAN-CVE-2026-22772, GHSA-59jp-pj84-45mr, GO-2026-4311, MINI-392x-774v-f573 and 27 more.