Vulnerability-Lookup

RHSA-2026:67147

Vulnerability from csaf_opensuse - Published: 2026-09-14 05:15 - Updated: 2026-09-25 15:30

Summary

Red Hat Security Advisory: python-tornado security update

Severity

Important

Notes

Topic: An update for python-tornado is now available for Red Hat Enterprise Linux 10. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Details: Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems. Security Fix(es): * tornado: Tornado: Information disclosure via improper handling of credentials during HTTP redirects (CVE-2026-49853) * tornado: Tornado: Denial of Service via uncontrolled gzip decompression memory consumption (CVE-2026-49855) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-49853

A flaw was found in Tornado's SimpleAsyncHTTPClient. When following a redirect to a different origin, the client improperly retains and forwards sensitive authentication credentials, such as Authorization headers, to the new, potentially untrusted, destination. This vulnerability allows a remote attacker to gain unauthorized access to a user's credentials, leading to information disclosure.

7.7 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

CWE-201 - Insertion of Sensitive Information Into Sent Data

Affected products

Fixed 13 products

Product	Version	Remediation
Unresolved product id: AppStream-10.2.Z:python-tornado-0:6.5.8-0.el10_2.1.src	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python-tornado-debugsource-0:6.5.8-0.el10_2.1.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python-tornado-debugsource-0:6.5.8-0.el10_2.1.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python-tornado-debugsource-0:6.5.8-0.el10_2.1.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python-tornado-debugsource-0:6.5.8-0.el10_2.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.x86_64	—	Vendor Fix fix Workaround

Threats

Impact Important

CVE-2026-49855

A flaw was found in Tornado, a Python web framework and asynchronous networking library. Its gzip decompression routines process data in limited-size chunks but do not enforce an overall limit on the total accumulated decompressed data. This vulnerability allows a malicious server to consume effectively unlimited memory, leading to a denial of service, when accessed by a client using SimpleAsyncHTTPClient or an HTTPServer configured with decompress_request set to true.

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-770 - Allocation of Resources Without Limits or Throttling

Affected products

Fixed 13 products, the same list as for CVE-2026-49853

Threats

Impact Important

References

17 references

URL	Category
https://access.redhat.com/errata/RHSA-2026:67147	self
https://access.redhat.com/security/updates/classi…	external
https://security.access.redhat.com/data/csaf/v2/a…	self
https://access.redhat.com/security/cve/CVE-2026-49853	self
https://bugzilla.redhat.com/show_bug.cgi?id=2500672	external
https://www.cve.org/CVERecord?id=CVE-2026-49853	external
https://nvd.nist.gov/vuln/detail/CVE-2026-49853	external
https://github.com/tornadoweb/tornado/commit/aba2…	external
https://github.com/tornadoweb/tornado/pull/3626	external
https://github.com/tornadoweb/tornado/releases/ta…	external
https://github.com/tornadoweb/tornado/security/ad…	external
https://access.redhat.com/security/cve/CVE-2026-49855	self
https://bugzilla.redhat.com/show_bug.cgi?id=2500686	external
https://www.cve.org/CVERecord?id=CVE-2026-49855	external
https://nvd.nist.gov/vuln/detail/CVE-2026-49855	external
https://github.com/tornadoweb/tornado/commit/ff80…	external
https://github.com/tornadoweb/tornado/security/ad…	external

JSON

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            "AppStream-10.2.Z:python-tornado-debugsource-0:6.5.8-0.el10_2.1.x86_64",
            "AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.aarch64",
            "AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.ppc64le",
            "AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.s390x",
            "AppStream-10.2.Z:python3-tornado-0:6.5.8-0.el10_2.1.x86_64",
            "AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.aarch64",
            "AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.ppc64le",
            "AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.s390x",
            "AppStream-10.2.Z:python3-tornado-debuginfo-0:6.5.8-0.el10_2.1.x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Important"
        }
      ],
      "title": "tornado: Tornado: Denial of Service via uncontrolled gzip decompression memory consumption"
    }
  ]
}

CVE-2026-49853 (GCVE-0-2026-49853)

Vulnerability from cvelistv5 – Published: 2026-07-14 20:41 – Updated: 2026-07-21 14:47

Title

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

Summary

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, SimpleAsyncHTTPClient shallow-copied redirected requests and removed only the Host header, leaving Authorization, auth_username, auth_password, and auth_mode in place when a redirect changed scheme, host, or port. This issue is fixed in version 6.5.6.

Severity

7.7 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-21 14:47 UTC

CWE

CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/tornadoweb/tornado/security/ad…	x_refsource_CONFIRM
https://github.com/tornadoweb/tornado/pull/3626	x_refsource_MISC
https://github.com/tornadoweb/tornado/commit/aba2…	x_refsource_MISC
https://github.com/tornadoweb/tornado/releases/ta…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
tornadoweb	tornado	Affected: < 6.5.6

Show details on NVD website

JSON

To clipboard

{
  "containers": {
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        "metrics": [
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CVE-2026-49855 (GCVE-0-2026-49855)

Vulnerability from cvelistv5 – Published: 2026-07-14 20:45 – Updated: 2026-07-16 14:56

Title

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

Summary

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.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-16 14:55 UTC

CWE

CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/tornadoweb/tornado/security/ad…	x_refsource_CONFIRM
https://github.com/tornadoweb/tornado/pull/3626	x_refsource_MISC
https://github.com/tornadoweb/tornado/commit/ff80…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
tornadoweb	tornado	Affected: < 6.5.6

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
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                "id": "CVE-2026-49855",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

RHSA-2026:67147

CVE-2026-49853 (GCVE-0-2026-49853)

CVE-2026-49855 (GCVE-0-2026-49855)

Tags

Sightings

Nomenclature

Related by attack behaviour