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CVE-2026-91991VulnerabilityPublished Updated

snakeviz · Tornado: Incomplete fix for CVE-2026-35536: cookie attribute injection re-opened via the legacy case-insensitive

Affects snakevizSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-91991· Medium 6.3

Not known to be exploited · CVSS 6.3 Medium : upgrade to 2.2.2_5 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.2.2_5
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 snakeviz to 2.2.2_5.

Affected software

ProductAffectedFixed in
Homebrewsnakevizpkg:brew/snakevizOther threatsAffected
  • >=2.2.2_3 <2.2.2_5
Fixed in
  • 2.2.2_5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available in Tornado version 2.2.2_5 that applies the same forbidden character validation to all cookie attribute keys, including those passed via the deprecated **kwargs path after normalizing key case. Users should upgrade to version 2.2.2_5 or later. Alternatively, removing the deprecated kwargs path or adding validation for capitalized keys can mitigate the issue. The vendor advisory confirms the patch availability.

Description

CVE-2026-91991 is a vulnerability in Tornado's set_cookie method where an incomplete fix for a previous cookie attribute injection flaw (CVE-2026-35536) allows injection via capitalized keyword arguments. The validation loop only checks lowercase keys, while the deprecated kwargs path accepts capitalized keys without validation, enabling injection of cookie attributes such as Secure, HttpOnly, SameSite, Domain, and Path. This can lead to manipulation of cookie attributes if the application uses capitalized keyword arguments. A patch is available in version 2.2.2_5 that addresses this issue.

References

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