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CVE-2026-0865

Good to know:

Date: January 20, 2026

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

Severity Score

4.9

Related Resources (11)

Url: https://github.com/python/cpython/commit/22e4d55285cee52bc4dbe061324e5f30bd4dee58

Url: https://nvd.nist.gov/vuln/detail/CVE-2026-0865

Url: https://github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510

Url: https://github.com/python/cpython/pull/143917

Url: https://github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211

Url: https://mail.python.org/archives/list/security-announce@python.org/thread/BJ6QPHNSHJTS3A7CFV6IBMCAP2DWRVNT/

Url: https://github.com/python/cpython/issues/143916

Url: https://github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2

Url: https://github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5

Url: https://github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995

Url: https://www.mend.io/vulnerability-database/CVE-2026-0865

Severity Score

4.9

Weakness Type (CWE)

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

CWE-74

CVSS v3.1

Base Score:	4.9
Attack Vector (AV):	NETWORK
Attack Complexity (AC):	LOW
Privileges Required (PR):	HIGH
User Interaction (UI):	NONE
Scope (S):	UNCHANGED
Confidentiality (C):	NONE
Integrity (I):	HIGH
Availability (A):	NONE

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