CVE-2026-77815 (CVSS 7.5)

Description

to_abs_path in scripts/iib/tool.py normalised the requested path with os.path.normpath, which collapses dot segments but does not resolve symbolic links. A symlink placed inside a scanned directory therefore satisfies the containment comparison performed by is_path_trusted in scripts/iib/api.py while pointing outside that directory, and FileResponse follows the link when serving the response, so a link created in an image directory and targeting a file such as /etc/passwd discloses that file. Whether the check applies depends on get_enable_access_control in scripts/iib/tool.py: it returns true when IIB_ACCESS_CONTROL is set to enable, false when set to disable, and otherwise true when the host Stable Diffusion WebUI was started with share, ngrok, listen or server_name, falling back to false. Confinement is therefore active in the network-exposed WebUI deployments that rely on it, while a standalone run with no such option serves every readable file regardless of this flaw. The fix resolves the path with os.path.realpath.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS — Exploit Prediction

0.0041

Probability of exploitation

0.35%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-59 CWE-59

References

Other References

Frequently Asked Questions

What is CVE-2026-77815? +

to_abs_path in scripts/iib/tool.py normalised the requested path with os.path.normpath, which collapses dot segments but does not resolve symbolic links. A symlink placed inside a scanned directory therefore satisfies the containment comparison performed by is_path_trusted in scripts/iib/api.py while pointing outside that directory, and FileResponse follows the link when serving the response, so a link created in an image directory and targeting a file such as /etc/passwd discloses that file. Whether the check applies depends on get_enable_access_control in scripts/iib/tool.py: it returns true when IIB_ACCESS_CONTROL is set to enable, false when set to disable, and otherwise true when the host Stable Diffusion WebUI was started with share, ngrok, listen or server_name, falling back to false. Confinement is therefore active in the network-exposed WebUI deployments that rely on it, while a standalone run with no such option serves every readable file regardless of this flaw. The fix resolves the path with os.path.realpath. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-77815? +

CVE-2026-77815 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0041, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-77815? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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