Cyber Resilience

CVE-2026-22772

SSRF in Linuxfoundation Fulcio ≤ 1.8.5

Public PoCSSRF
Published
12 January 2026
Modified
05 March 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
EPSS Score 0.0022 13th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-22772 is a medium-severity SSRF (CWE-918) vulnerability in Linuxfoundation Fulcio. Its CVSS base score is 5.8 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 13th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-918

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1046 Network Service Discovery Discovery
Adversaries may attempt to get a listing of services running on remote hosts and local network infrastructure devices, including those that may be vulnerable to remote software exploitation.
attack.mitre.org →
Why these techniques?

SSRF vuln in public-facing Fulcio enables exploitation of the app (T1190) and blind internal network probing/service discovery (T1046).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-32236Same vendor: Linuxfoundation
CVE-2025-66506Same product: Linuxfoundation Fulcio
CVE-2026-24048Same vendor: Linuxfoundation
CVE-2026-24117Same vendor: Linuxfoundation
CVE-2025-59346Same vendor: Linuxfoundation
CVE-2025-61916Same vendor: Linuxfoundation
CVE-2024-13924Shared CWE-918
CVE-2025-68139Same vendor: Linuxfoundation
CVE-2026-4979Shared CWE-918
CVE-2024-51242Shared CWE-918

Affected Assets

linuxfoundation
fulcio
≤ 1.8.5

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SC-7 Boundary Protection
  • AC-4 Information Flow Enforcement
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.3.6
  • V1.5.3
  • V5.3.2
  • V10.4.7

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match
prevent

Directly requires validation of URL/MetaIssuer inputs to reject malformed or unanchored patterns that enable SSRF bypass.

SC-7 Boundary Protection partial match
prevent

Enforces boundary controls that can restrict or deny the outbound GET requests used for blind internal network probing.

AC-4 Information Flow Enforcement partial match
prevent

Enforces information flow policies on external URLs to block unauthorized SSRF destinations before requests are issued.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure development practices directly include input validation and destination allow-listing that prevent SSRF.

DE.CM-09 partial match
prevents

Runtime monitoring of web applications and services can detect anomalous outbound requests indicative of SSRF.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover and record SSRF flaws in web applications.

PR.IR-01 partial match
prevents

Network segmentation and egress controls can limit the damage from successful SSRF requests.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.7 Threat intelligence partial match
prevents

Operational threat data describing SSRF campaigns can be used to tighten outbound-request allow-lists and detection rules before attackers exploit them.

References