Python CPython up to 3.14.x http.cookies.Morsel input validation

CVSS Meta Temp Score
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CTI Interest Score
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6.7$0-$5k0.00

Summaryinfo

A vulnerability was found in Python CPython up to 3.14.x. It has been rated as critical. This affects the function http.cookies.Morsel. Performing a manipulation results in input validation. This vulnerability is cataloged as CVE-2026-3644. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in Python CPython up to 3.14.x. This affects the function http.cookies.Morsel. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

The advisory is shared at mail.python.org. This vulnerability is uniquely identified as CVE-2026-3644 since 03/06/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 302532 (Linux Distros Unpatched Vulnerability : CVE-2026-3644), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.15.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (302532), EUVD (EUVD-2026-12484) and CERT Bund (WID-SEC-2026-0741). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Fedora Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Python

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.9
VulDB Meta Temp Score: 6.7

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 302532
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-3644

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: CPython 3.15.0

Timelineinfo

03/06/2026 CVE reserved
03/16/2026 +10 days Advisory disclosed
03/16/2026 +0 days VulDB entry created
06/24/2026 +99 days VulDB entry last update

Sourcesinfo

Advisory: mail.python.org
Status: Confirmed

CVE: CVE-2026-3644 (🔒)
GCVE (CVE): GCVE-0-2026-3644
GCVE (VulDB): GCVE-100-351309
EUVD: 🔒
CERT Bund: WID-SEC-2026-0741 - CPython: Mehrere Schwachstellen ermöglichen Manipulation von Dateien und DoS

Entryinfo

Created: 03/16/2026 19:20
Updated: 06/24/2026 01:54
Changes: 03/16/2026 19:20 (67), 03/17/2026 08:40 (1), 03/19/2026 04:35 (2), 03/21/2026 14:09 (1), 04/24/2026 23:20 (7), 06/05/2026 00:10 (11), 06/24/2026 01:54 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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