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Description

Banana Slides through 0.4.0, patched in commit e8bc490, contains a path traversal vulnerability in the generate_image() function within the AI service backend that allows unauthenticated attackers to read arbitrary image-format files outside the intended uploads directory by exploiting an incomplete path prefix check using os.path.startswith() without a trailing separator. Attackers can supply crafted markdown image references in user-controlled page descriptions that resolve to sibling directories whose names share the uploads folder prefix, bypassing the directory confinement check and causing the application to read files from unintended locations via PIL Image.open().

PUBLISHED Reserved 2026-05-27 | Published 2026-06-01 | Updated 2026-06-02 | Assigner VulnCheck




HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem types

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Product status

Default status
affected

Any version
affected

e8bc490ec8b4b657e07dc3ab4e94fbedcaade421 (git)
unaffected

Credits

YU SUN finder

References

github.com/Anionex/banana-slides/issues/429 technical-description exploit

github.com/Anionex/banana-slides/pull/430 issue-tracking

github.com/...ommit/e8bc490ec8b4b657e07dc3ab4e94fbedcaade421 patch

www.vulncheck.com/...sal-via-generate-image-in-ai-service-py third-party-advisory

cve.org (CVE-2026-49136)

nvd.nist.gov (CVE-2026-49136)

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