Vulnerability in Emilstenstrom Justhtml
CVE-2026-9769
justhtml through 1.9.1 (fixed in 1.10.0) is vulnerable to uncontrolled recursion leading to denial of service. During JustHTML() construction, TreeBuilder.finish() unconditionally calls _populate_selectedcontent(), which recursively traverses the DOM tree via _find_elements()/_find_element() without a depth bound. An attacker who can supply HTML for parsing can provide deeply nested elements (e.g., ~1000 nested <div> tags, roughly 11 KB) to exceed CPython's default recursion limit and trigger an unhandled RecursionError, which may abort parsing, fail requests, or terminate a worker/process depending on the host application's exception handling.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- github.com/EmilStenstrom/justhtml/security/advisories/GHSA-v7cf-c9rm-wm3j (vendor-advisory)
- www.vulncheck.com/advisories/justhtml-before-denial-of-service-via-deeply-neste… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-9769?
- CVE-2026-9769 is a high-severity vulnerability in Emilstenstrom Justhtml, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-08-23.
- How severe is CVE-2026-9769?
- High severity. CVSS v3 base score is 7.5 out of 10.