CVE-2026-107466 Red Hat CVE debrief

Who should care

Defenders responsible for CI systems, developers using flatpak-builder, and administrators of environments where flatpak-builder is used should assess exposure and verify the integrity of their build environments.

Why it matters

CVE-2026-107466 allows information disclosure via crafted build manifests in flatpak-builder, impacting CI systems and users processing untrusted manifests. Defenders should verify and update instances, restrict access to sensitive files, and monitor for unusual patterns.

• Sensitive information disclosure through build artifacts.
• Potential for unauthorized access to host files.
• Need for verification of flatpak-builder instances and update to latest versions.
• Possible disruption of CI systems due to crafted build manifests.

Technical summary

The vulnerability in flatpak-builder allows an attacker to bypass directory confinement checks by specifying local file URIs within source download definitions in a crafted build manifest. This can lead to the reading of sensitive host files accessible to the build process and their incorporation into build artifacts. The vulnerability impacts CI systems and users processing untrusted build manifests, allowing for information disclosure. Defenders should prioritize verifying and updating flatpak-builder instances, especially in environments where CI systems or users process untrusted build manifests.

Defensive priority

Defenders should prioritize verifying and updating flatpak-builder instances, especially in environments where CI systems or users process untrusted build manifests.

Recommended defensive actions

• Verify and update flatpak-builder instances to the latest version.
• Restrict access to sensitive host files for CI systems and users processing build manifests.
• Implement additional monitoring for unusual file access patterns in build environments.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source item provide details on the vulnerability in flatpak-builder, including its impact on information disclosure. The vulnerability allows an attacker to bypass directory confinement checks by specifying local file URIs within source download definitions in a crafted build manifest. This can lead to the reading of sensitive host files accessible to the build process and their incorporation into build artifacts. Defenders should verify the integrity of their build environments and monitor for unusual patterns. The

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.