sickchill · Tornado: Incomplete fix for CVE-2026-35536: cookie attribute injection re-opened via the legacy case-insensitive
Affects sickchillSource GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 6.3 Medium : upgrade to 2024.3.1_8 when convenient.
Data as of 30 Oct 2026, 07:30 UTC
- Patch
- Available – fixed in 2024.3.1_8
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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
## Summary The CVE-2026-35536 fix added a validation loop that rejects `[\x00-\x20\x3b\x7f]`, but only for the hardcoded **lowercase** keys `name`/`domain`/`path`/`samesite`. The still-live deprecated `**kwargs` path writes attacker-supplied attribute values straight into the `Morsel` with no validation, and because `Morsel.__setitem__` is case-insensitive, a capitalized kwarg (`Domain=`, `Path=`, `SameSite=`, `Max-Age=`) routes to the same reserved attribute while bypassing the loop — re-opening `;`-delimited attribute injection. ```python self.set_cookie("sid", "abc", Domain="evil.com; Secure; SameSite=None") # -> Set-Cookie: sid=abc; Domain=evil.com; Secure; SameSite=None; Path=/ # Sanity (the canonical lowercase named arg IS blocked): self.set_cookie("sid", "abc", domain="evil.com; Secure") # -> http.cookies.CookieError ``` The patch's regression test (`SetCookieForbiddenCharHandler`) only exercises the four named params, never the `**kwargs` path, so the gap is not regression-covered. ## Affected code - `tornado/web.py` → `RequestHandler.set_cookie`: the validation loop covers only the lowercase named args; the trailing `if kwargs:` loop does `morsel[k] = v` with no character validation. ## Steps to reproduce `GET /upper` (uses `Domain=` kwarg) emits `Set-Cookie: c_upper=v; Domain=evil.com; Secure; SameSite=None; Path=/`; `GET /lower` (uses lowercase `domain=`) returns a `CookieError`. ## Impact Injection of independent cookie attributes (force/drop `Secure`/`HttpOnly`/`SameSite`, rebind `Domain`/`Path`) — the same impact CVE-2026-35536 closed, via the sibling path the patch missed. Conditional on the app using a capitalized/legacy keyword. ## Suggested remediation Apply the same `[\x00-\x20\x3b\x7f]` validation to every entry in the `**kwargs` loop (after normalizing the key case), or remove the deprecated kwargs path; add a regression test for capitalized kwargs. ## Credit Reported as part of an incomplete-patch measurement study (responsible disclosure).
References
- github.com/tornadoweb/tornado/security/advisories/GHSA-wwv5-g3v4-889x (opens in a new tab)
- github.com/tornadoweb/tornado/pull/3704 (opens in a new tab)
- github.com/tornadoweb/tornado/pull/3706 (opens in a new tab)
- github.com/tornadoweb/tornado/commit/6ef836e43e1278530041376adb32504daa977b91 (opens in a new tab)
- github.com/tornadoweb/tornado/commit/da284767eae8e1f0484f123b8c3225f6465b09c7 (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)