Gitea Runner: Host isolation bypass via container options
Summary
Gitea Runner does not fully remove workflow-controlled container options (such as host namespace settings, capabilities and security profile overrides) when privileged mode is disabled. A workflow author who can run jobs on an affected Docker-backed runner can use these options to access host namespaces and execute commands as root on the runner host, bypassing container isolation. The attack requires a valid account that can submit or trigger workflows; the CVSS base score is disputed between sources (8.8 in the provided record, 9.9 in the GitHub/OSV record).
Affected
- Gitea Runner (act_runner) versions before 3.0.0
- Only Docker-backed runners without privileged mode are affected by the container options issue
Fixed in
- Upgrade to Gitea Runner v3.0.0 (released 2026-07-31)
Workaround
- Unknown. Vendor fix is available; do not enable privileged mode as a workaround, as this keeps the dangerous options active.
- Until upgraded, restrict who can trigger workflows on Docker-backed runners and review workflows for container.options entries.
Exploitation
- No public proof-of-concept known at the time of writing.
- No report of active exploitation known; CISA SSVC assessment: exploitation none, automatable no, technical impact total.
Our recommendation
- Upgrade all Docker-backed Gitea Runner instances to v3.0.0 or later.
- Until the upgrade is done, limit workflow execution to trusted users and avoid untrusted forks or open registration on shared runners.
- Review workflows for container.options entries such as PidMode, CapAdd, SecurityOpt, Devices or Sysctls, and check whether they still work after the upgrade.
- Consider running runners in disposable VMs and do not keep CI secrets or deploy keys on the runner host.
- Monitor runner hosts for unexpected root activity.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Gitea Runner 3.0.0 is released (Gitea Blog) blog.gitea.com
- Gitea Runner v3.0.0 release gitea.com
- GHSA-x4q3-gcj3-m6cf (GitHub Security Advisory) github.com
- Go advisory CVE-2026-73802 (GitLab Advisory Database) advisories.gitlab.com
- OSV GHSA-x4q3-gcj3-m6cf osv.dev
- Gitea Runner configuration documentation docs.gitea.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 16:50.
Original description (NVD)
Gitea Runner passes workflow-controlled container options into Docker job container configuration while privileged mode is disabled. Host namespace settings, expanded capabilities, and security profile overrides can remain effective despite Privileged being forced false. A workflow author able to run jobs on an affected Docker-backed runner can use these options to access host namespaces and execute commands as root on the runner host, bypassing the intended container isolation.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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