CVE catalog
CVE-2026-49855
Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, Tornado gzip decompression routines processed limited-size chunks but did not enforce an overall limit on accumul
- Severity
- High · CVSS 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.57% · Oct 25, 2026
Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, Tornado gzip decompression routines processed limited-size chunks but did not enforce an overall limit on accumulated decompressed chunks, allowing a malicious server accessed by SimpleAsyncHTTPClient or an HTTPServer configured with decompress_request=True to consume effectively unlimited memory. This issue is fixed in version 6.5.6.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | python-tornado | sid | 6.5.5-5 | vulnerable |
| Debian | python-tornado | forky | 6.5.5-5 | vulnerable |
| Debian | python-tornado | trixie | 6.4.2-3+deb13u2 | vulnerable |
| Debian | python-tornado | trixie-security | 6.4.2-3+deb13u2 | vulnerable |
| Debian | python-tornado | bookworm | 6.2.0-3+deb12u4 | vulnerable |
| Debian | python-tornado | bookworm-security | 6.2.0-3+deb12u4 | vulnerable |
| Cpe | python-tornado | Not reported | Not reported | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-1build1 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-2 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3build1 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3ubuntu0.1~esm1 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3ubuntu0.1~esm2 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3ubuntu0.1~esm4 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3ubuntu0.1~esm5 | vulnerable |
| Ubuntu | python-tornado | pro | 6.1.0-3ubuntu0.1~esm6 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.3.2-1 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-0ubuntu1 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1build1 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1ubuntu0.1 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1ubuntu0.2 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1ubuntu0.4 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1ubuntu0.5 | vulnerable |
| Ubuntu | python-tornado | 24.04 | 6.4.0-1ubuntu0.6 | vulnerable |
| Ubuntu | python-tornado | 26.10 | 6.5.4-0.1 | vulnerable |
| Ubuntu | python-tornado | 26.10 | 6.5.5-2 | vulnerable |
| Ubuntu | python-tornado | 26.10 | 6.5.5-4 | vulnerable |
| Ubuntu | python-tornado | 26.10 | 6.5.5-5 | vulnerable |
| Ubuntu | python-tornado | 26.10 | 6.5.5-5ubuntu1.1 | vulnerable |
| Ubuntu | python-tornado | 26.04 | 6.4.2-3 | vulnerable |
| Ubuntu | python-tornado | 26.04 | 6.5.2-3 | vulnerable |
| Ubuntu | python-tornado | 26.04 | 6.5.4-0.1 | vulnerable |
| Ubuntu | python-tornado | 26.04 | 6.5.4-0.1ubuntu0.1 | vulnerable |
| Ubuntu | python-tornado | 26.04 | 6.5.4-0.1ubuntu0.2 | vulnerable |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | python-tornado | source | sid | (unfixed) | not yet assigned | Not reported | [1142277] |
| Debian | python-tornado | source | forky | (unfixed) | not yet assigned | Not reported | [1142277] |
| Debian | python-tornado | source | trixie | (unfixed) | not yet assigned | Not reported | [1142277] |
| Debian | python-tornado | source | bookworm | (unfixed) | not yet assigned | Not reported | [1142277] |
Notes
[trixie] python-tornado: Minor issue
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [python3-tornado]Affected
Source package: [python-tornado]
Details (4)
6.2.0-3+deb12u4· amd64 · bookwormAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
6.2.0-3+deb12u4· arm64 · bookwormAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
6.2.0-3+deb12u4· amd64 · bookworm-securityAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
6.2.0-3+deb12u4· arm64 · bookworm-securityAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
- [python-tornado-doc]Affected
Source package: [python-tornado]
Details (4)
6.2.0-3+deb12u4· all · bookwormAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
6.2.0-3+deb12u4· all · bookwormAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
6.2.0-3+deb12u4· all · bookworm-securityAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
6.2.0-3+deb12u4· all · bookworm-securityAffected
nvd · python-tornado · debian · bookworm; nvd · python-tornado · debian · 12
[Debian 13 (Trixie)]
- [python3-tornado]Affected
Source package: [python-tornado]
Details (4)
6.4.2-3+deb13u2· amd64 · trixieAffected
nvd · python-tornado · debian · 13
6.4.2-3+deb13u2· arm64 · trixieAffected
nvd · python-tornado · debian · 13
6.4.2-3+deb13u2· amd64 · trixie-securityAffected
nvd · python-tornado · debian · 13
6.4.2-3+deb13u2· arm64 · trixie-securityAffected
nvd · python-tornado · debian · 13
- [python-tornado-doc]Affected
Source package: [python-tornado]
Details (4)
6.4.2-3+deb13u2· all · trixieAffected
nvd · python-tornado · debian · 13
6.4.2-3+deb13u2· all · trixieAffected
nvd · python-tornado · debian · 13
6.4.2-3+deb13u2· all · trixie-securityAffected
nvd · python-tornado · debian · 13
6.4.2-3+deb13u2· all · trixie-securityAffected
nvd · python-tornado · debian · 13
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/rhsa-2026_67146.json]
- [https://github.com/tornadoweb/tornado/commit/ff808b33adc52d89a549376a5e3628e92abbc8ff]
- [https://github.com/tornadoweb/tornado/pull/3626]
- [https://github.com/tornadoweb/tornado/security/advisories/GHSA-mgf9-4vpg-hj56]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-49855]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-49855]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2026-49855]
- [https://security-tracker.debian.org/tracker/CVE-2026-49855]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-49855.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-3870.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]