sickchill · tornado: multipart split() creates huge temp list before max_parts check -> memory amplification DoS (httputil.py:34)
Affects sickchillSource GCVE Database
Not known to be exploited · CVSS 8.7 High : upgrade to 2024.3.1_8 soon.
Data as of 30 Oct 2026, 07:30 UTC
- Patch
- Available – fixed in 2024.3.1_8
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 15 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade sickchill to 2024.3.1_8.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewsickchillpkg:brew/sickchillOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
## Description ### Summary `parse_multipart_form_data` (httputil.py:34) calls `data.split(b"--"+boundary+b"\r\n")` **before** the `max_parts` check (:35). A 600KB body with 100k parts creates a 100k-element transient list first, then rejects transient memory amplification (each split element is a copy). Pre-auth HTTP DoS. ### Root cause ```python parts = data[:final_boundary_index].split(b"--" + boundary + b"\r\n") # :34 huge list first if len(parts) > config.max_parts: # :35 check after raise HTTPInputError("multipart/form-data has too many parts") ``` ### PoC gist: https://gist.github.com/afldl/649861f25d39b53b7edbe0298e171617 `poc.py` + `output.txt` (100k parts from 600KB transient list). ### Fix Count separators without materializing the list (e.g. `data.count(b"--"+boundary)` first). ### Credit Reported by afldl, 2026-07.
References
- github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq (opens in a new tab)
- github.com/tornadoweb/tornado/pull/3704 (opens in a new tab)
- github.com/tornadoweb/tornado/commit/de85b3f87446e323e881bbaa3d5a74f4b76e5f05 (opens in a new tab)
- gist.github.com/afldl/649861f25d39b53b7edbe0298e171617 (opens in a new tab)
- github.com/tornadoweb/tornado (opens in a new tab)
- github.com/tornadoweb/tornado/releases/tag/v6.5.8 (opens in a new tab)