Service interruption via unbounded DOM recursion
Published Aug 23, 2026 · Updated Aug 23, 2026
Uncontrolled recursion in JustHTML through 1.9.1 allows remote attackers to interrupt parsing via deeply nested HTML. TreeBuilder.finish() unconditionally invokes _populate_selectedcontent(), whose _find_elements() and _find_element() traversals descend the attacker-controlled DOM without a depth bound until CPython raises an unhandled RecursionError. Reachability requires an application or CLI workflow to parse attacker-supplied HTML; the interruption ranges from an aborted parse or failed request to worker or process termination, depending on host exception handling.
Summary
What happened
Uncontrolled recursion in JustHTML through 1.9.1 allows remote attackers to interrupt parsing via deeply nested HTML. TreeBuilder.finish() unconditionally invokes _populate_selectedcontent(), whose _find_elements() and _find_element() traversals descend the attacker-controlled DOM without a depth bound until CPython raises an unhandled RecursionError. Reachability requires an application or CLI workflow to parse attacker-supplied HTML; the interruption ranges from an aborted parse or failed request to worker or process termination, depending on host exception handling.
The record
- CVE
- CVE-2026-9769
- Published
- Aug 23, 2026
- Updated
- Aug 23, 2026
- Vendor
- Emil Stenström
- Product
- JustHTML
- Classifications
- CWE-674, CAPEC-230, CAPEC-231, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 23, 2026CVE publishedPublication date reported by the CVE source.
- Aug 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.10.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Nested-div RecursionError reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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