CVE-2026-1299
Description
A flaw was found in the email module in the Python standard library. When serializing an email message, the BytesGenerator class fails to properly quote newline characters for email headers. This issue is exploitable when the LiteralHeader class is used as it does not respect email folding rules, allowing an attacker to inject email headers and potentially modify message recipients or the email body, and spoof sender information.
Statement
This issue can only be exploitable by Python applications using the LiteralHeader class to write email headers, as it does not respect email folding rules. Additionally, this issue allows attackers to modify message recipients or the email body and spoof sender identity but it does not cause memory corruption or arbitrary code execution. Due to these reasons, this vulnerability has been rated with a moderate severity.
Mitigation
To mitigate this issue, applications accepting user-supplied data for email headers should sanitize the input by stripping or rejecting any strings containing carriage return or line feed characters, '\r' or '\n', respectively, preventing malicious sequences that could lead to header manipulation.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.1 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | Low | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data
Frequently Asked Questions
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