Vulnerability in Thclaws
CVE-2026-108839
thClaws through 0.141.0 contains a link-following vulnerability in the post_inputs handler of the v1 API POST /v1/inputs endpoint that allows writes outside the workspace by following symlinks. Attackers who plant a symlink under the allowed inputs/ prefix can cause later authenticated uploads to write or truncate files outside the workspace with daemon privileges.
Published .
CVSS v3 metric
CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/thclaws-api-inputs-symlink-escape (third-party-advisory)
- github.com/thClaws/thClaws/blob/v0.141.0/crates/core/src/api_v1/artifacts.rs (technical-description)
- github.com/thClaws/thClaws (product)
- www.vulncheck.com/advisories/thclaws-through-0.141.0-symlink-following-file-wri… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-108839?
- CVE-2026-108839 is a medium-severity vulnerability in Thclaws, classified under Improper Link Resolution Before File Access. CVSS score: 4.2/10. Published 2026-10-11.
- How severe is CVE-2026-108839?
- Medium severity. CVSS v3 base score is 4.2 out of 10.