Python CPython up to 3.14.x HTTP Header injection

CVSS Meta Temp Score
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CTI Interest Score
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7.0$0-$5k0.00

Summaryinfo

A vulnerability was found in Python CPython up to 3.14.x. It has been rated as problematic. The impacted element is an unknown function of the component HTTP Header Handler. The manipulation leads to injection. This vulnerability is documented as CVE-2026-0865. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Python CPython up to 3.14.x and classified as critical. This issue affects an unknown function of the component HTTP Header Handler. The manipulation with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

User-controlled header names and values containing newlines can allow injecting HTTP headers.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-0865 since 01/12/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1055 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 296553 (Debian dla-4455 : idle-python3.9 - security update), 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 (296553), EUVD (EUVD-2026-3520) and CERT Bund (WID-SEC-2026-0209). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Python
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

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: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Injection
CWE: CWE-74 / CWE-707 / 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: 296553
Nessus Name: Debian dla-4455 : idle-python3.9 - security update

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: CPython 3.15.0

Timelineinfo

01/12/2026 CVE reserved
01/20/2026 +8 days Advisory disclosed
01/20/2026 +0 days VulDB entry created
04/22/2026 +92 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-0865 (🔒)
GCVE (CVE): GCVE-0-2026-0865
GCVE (VulDB): GCVE-100-342041
EUVD: 🔒
CERT Bund: WID-SEC-2026-0209 - Cpython: Mehrere Schwachstellen

Entryinfo

Created: 01/20/2026 23:28
Updated: 04/22/2026 10:12
Changes: 01/20/2026 23:28 (68), 01/21/2026 00:22 (1), 01/26/2026 07:44 (2), 02/02/2026 10:02 (7), 03/11/2026 06:08 (1), 03/11/2026 18:36 (1), 03/24/2026 20:44 (1), 04/22/2026 10:12 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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