StackPrism

PyPI package

tornado 6.5.5 vulnerabilities, and the version that fixes all of them

tornado 6.5.5 has 10 known vulnerabilities (5 rated high or critical); 6.5.9 fixes all of them.

PyPI (opens in a new tab) describes it as “Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.”

Known vulnerabilities
10
5 rated high or critical
Released
Mar 10, 2026
Latest is 6.5.10
Licence
Apache-2.0
OpenSSF Scorecard
6.6/10
tornadoweb/tornado (opens in a new tab)
Dependencies
None
Resolved by deps.dev

What to upgrade to

6.5.9 is the closest release with no known vulnerabilities.

  • 6.5.9Upgrade to this

    Fixes all 10 known vulnerabilities. Released Sep 14, 2026.

    No known vulnerabilities

  • 6.5.10

    Newest 6.x release and the latest release. Released Sep 15, 2026.

    No known vulnerabilities

6.5.9 came out on Sep 14, 2026. A coding agent trained before then doesn’t know it exists, so it may suggest an older release. AI knowledge cutoff dates

Hand the fix to your coding agent

One task with the upgrade, the file to change and why. Paste it into Claude Code, Cursor or Codex.

Findings

Every advisory for tornado 6.5.5

Known exploited first (CISA KEV), then by how likely they are to be exploited (FIRST EPSS), then by severity. Each id links to its OSV.dev record.

  1. CriticalCVE-2026-49855 on OSV.dev (opens in a new tab)GHSA-mgf9-4vpg-hj56EPSS: top 52%

    tornado AsyncHTTPClient accumulates decompressed chunks without size limit (gzip bomb)

    Fixed in 6.5.6. Published Jun 15, 2026.

  2. CriticalCVE-2026-103262 on OSV.dev (opens in a new tab)GHSA-chx6-46f5-w4vpEPSS: top 57%

    tornado: CurlAsyncHTTPClient enforces no response-size limit — decompression bomb drives unbounded memory accumulation to OOM

    Fixed in 6.5.9. Published Sep 30, 2026.

  3. CriticalCVE-2026-103263 on OSV.dev (opens in a new tab)GHSA-c2m8-h5v5-343rEPSS: top 57%

    Tornado: StaticFileHandler follows symlinks outside static root (path traversal)

    Fixed in 6.5.9. Published Sep 30, 2026.

  4. WarningCVE-2026-103261 on OSV.dev (opens in a new tab)GHSA-3hv7-mjh2-fv65EPSS: top 61%

    Tornado: Unbounded query-string argument count allows event-loop-stalling DoS

    Fixed in 6.5.9. Published Sep 30, 2026.

  5. CriticalCVE-2026-49853 on OSV.dev (opens in a new tab)GHSA-3x9g-8vmp-wqvfEPSS: top 63%

    Tornado: Authorization header forwarded across cross-origin redirects in SimpleAsyncHTTPClient

    Fixed in 6.5.6. Published Jun 15, 2026.

  6. WarningCVE-2026-91990 on OSV.dev (opens in a new tab)GHSA-8423-8fgw-73vqEPSS: top 65%

    tornado: multipart split() creates huge temp list before max_parts check -> memory amplification DoS (httputil.py:34)

    Fixed in 6.5.8. Published Sep 1, 2026.

  7. LowCVE-2026-49854 on OSV.dev (opens in a new tab)GHSA-cx3h-4qpv-8hc9EPSS: top 66%

    Tornado has out-of-bounds memory access via C extension

    Fixed in 6.5.6. Published Jun 12, 2026.

  8. CriticalCVE-2026-82397 on OSV.dev (opens in a new tab)GHSA-mpf4-983q-p7j4EPSS: top 74%

    Tornado: Urlencoded body parsing omits max_num_fields, so one request can stall the event loop

    Fixed in 6.5.8. Published Sep 2, 2026.

  9. WarningCVE-2026-91992 on OSV.dev (opens in a new tab)GHSA-pw6j-qg29-8w7fEPSS: top 84%

    Tornado: CurlAsyncHTTPClient leaks per-request credentials on handle reuse

    Fixed in 6.5.7. Published Jun 15, 2026.

  10. LowCVE-2026-91991 on OSV.dev (opens in a new tab)GHSA-wwv5-g3v4-889xEPSS: top 86%

    Tornado: Incomplete fix for CVE-2026-35536: cookie attribute injection re-opened via the legacy case-insensitive `**kwargs` path in `set_cookie`

    Fixed in 6.5.8. Published Sep 1, 2026.

Is tornado the only one?

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How this page is checked

StackPrism asks OSV.dev which advisories affect exactly tornado 6.5.5, merges duplicates filed under several ids, and ranks them with CISA’s Known Exploited Vulnerabilities list and FIRST EPSS. Release dates and deprecation come from deps.dev and PyPI. No AI writes this page: every sentence comes from that data, refreshed every few hours.

Last checked against PyPI, OSV.dev, deps.dev, CISA KEV and FIRST EPSS.