Summary
A path traversal vulnerability (Zip Slip) exists in the media archive import feature. An authenticated user with owner-level privileges can craft a malicious ZIP file with directory-traversal filenames to write arbitrary files outside the intended temporary extraction directory on the server's local filesystem.
Details
When importing media archives as ZIP file, MediaImporter._check_disk_space_and_extract() in gramps_webapi/api/media_importer.py called zipfile.extractall() without validating ZIP entry names. Python's zipfile module does not sanitize entry names containing ../ sequences, allowing extraction to paths outside the target directory.
Only users with owner permission can upload media ZIP archives, so the biggest risk is for multi-tree deployments, where tree owners are distinct from server administrators.
For multi-tree deployments, the impact depends on deployment configuration. Assuming the standard docker-based deployment is used:
- SQLite family tree + local media: An attacker can overwrite another tree's database file or media files, leading to cross-tree data corruption or replacement.
- Postgres family tree + S3 media: No persistent tree data is stored on the local filesystem, so cross-tree impact is eliminated. The remaining risk is overwriting volume-mounted files such as the application config file.
- Postgres family tree + S3 media + environment-variable-only config: No persistent files of value are present on the local filesystem. Impact is limited to writes to ephemeral container storage, which are lost on woker restart.
Impact
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-40258 has a CVSS score of 9.1 (Critical). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.11.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
ZIP entry names are now validated against the resolved real path of the temporary directory before extraction. Any entry whose resolved path falls outside the temporary directory raises an error and aborts the import.
Frequently Asked Questions
- What is CVE-2026-40258? CVE-2026-40258 is a critical-severity path traversal vulnerability in gramps-webapi (pip), affecting versions >= 1.6.0, <= 3.11.0. It is fixed in 3.11.1. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2026-40258? CVE-2026-40258 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of gramps-webapi are affected by CVE-2026-40258? gramps-webapi (pip) versions >= 1.6.0, <= 3.11.0 is affected.
- Is there a fix for CVE-2026-40258? Yes. CVE-2026-40258 is fixed in 3.11.1. Upgrade to this version or later.
- Is CVE-2026-40258 exploitable, and should I be worried? Whether CVE-2026-40258 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-40258 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-40258? Upgrade
gramps-webapito 3.11.1 or later.