CVE-2026-1299

UNSCORED

Description

The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when serializing an email message allowing for header injection when an email is serialized. This is only applicable if using "LiteralHeader" writing headers that don't respect email folding rules, the new behavior will reject the incorrectly folded headers in "BytesGenerator".

CWE-93

How to fix

Remediation Available

pypy3Debian

Fixed in:7.3.21+dfsg-1CVE-2026-1299

platform-pythonRocky

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

platform-pythonRed Hat / RHEL

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

platform-python-debugRocky

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

platform-python-debugRed Hat / RHEL

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

platform-python-develRocky

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

platform-python-develRed Hat / RHEL

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-39.el8_4.9RHSA-2026:5221

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

python-unversioned-commandRed Hat / RHEL

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.9.10-4.el9_0.9RHSA-2026:5219

Fixed in:0:3.9.18-3.el9_4.11RHSA-2026:5226

Fixed in:0:3.9.21-2.el9_6.4RHSA-2026:5218

Fixed in:0:3.9.25-3.el9_7.1RHSA-2026:4168

Fixed in:0:3.9.16-1.el9_2.12RHSA-2026:5225

python-unversioned-commandRocky

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.9.21-2.el9_6.4RHSA-2026:5218

Fixed in:0:3.9.25-3.el9_7.1RHSA-2026:4168

Fixed in:0:3.9.18-3.el9_4.11RHSA-2026:5226

Fixed in:0:3.9.10-4.el9_0.9RHSA-2026:5219

Fixed in:0:3.9.16-1.el9_2.12RHSA-2026:5225

python3Red Hat / RHEL

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3Rocky

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3-debugRed Hat / RHEL

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3-debugRocky

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3-debuginfoRocky

Fixed in:0:3.6.8-21.el7_9.4RHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4.ppcRHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4RHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4.ppc64RHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4.s390RHSA-2026:6464

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

python3-debuginfoRed Hat / RHEL

Fixed in:0:3.6.8-21.el7_9.4RHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4.ppcRHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4RHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4.s390RHSA-2026:6464

Fixed in:0:3.6.8-21.el7_9.4.ppc64RHSA-2026:6464

Fixed in:0:3.6.8-24.el8_2.6RHSA-2026:5216

python3-debugsourceRed Hat / RHEL

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

python3-debugsourceRocky

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-51.el8_8.13RHSA-2026:6008

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

Fixed in:0:3.6.8-47.el8_6.11RHSA-2026:5215

Fixed in:0:3.6.8-73.el8_10RHSA-2026:2128

python3-develRed Hat / RHEL

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

python3-develRocky

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

python3-idleRocky

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

python3-idleRed Hat / RHEL

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3-libsRocky

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3-libsRed Hat / RHEL

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3-testRed Hat / RHEL

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

python3-testRocky

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

python3-tkinterRed Hat / RHEL

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

python3-tkinterRocky

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

Fixed in:0:3.12.12-3.el10_1.1RHSA-2026:4713

Fixed in:0:3.12.9-2.el10_0.7RHSA-2026:5315

python3.11Rocky

Fixed in:0:3.11.2-2.el8_8.8RHSA-2026:5152

Fixed in:0:3.11.13-5.el8_10RHSA-2026:4473

Fixed in:0:3.11.2-2.el8_8.8RHSA-2026:5152

python3.11Red Hat / RHEL

Fixed in:0:3.11.13-5.el8_10RHSA-2026:4473

Fixed in:0:3.11.2-2.el8_8.8RHSA-2026:5152

Fixed in:0:3.11.13-5.el8_10RHSA-2026:4473

Fixed in:0:3.11.2-2.el8_8.8RHSA-2026:5152

Fixed in:0:3.11.13-5.el8_10RHSA-2026:4473

python3.11-debugRocky

Fixed in:0:3.11.13-5.el8_10RHSA-2026:4473

Fixed in:0:3.11.13-5.1.el9_7RHSA-2026:4216

Fixed in:0:3.11.7-1.el9_4.11RHSA-2026:6253

This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3.1 Vector

No CVSS vector data available.

Exploit Intelligence

0.53%probability of exploitation in 30 days

43rdpercentile

Moderate risk: more likely to be exploited than 43% of all known CVEs.

References

Other references10

Related Vulnerabilities

Other CWE-93 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-61884	High	7.5	98%	KEV + Ransom	-
CVE-2022-0666	High	7.5	44%	-	Fix
CVE-2016-3115	Medium	6.4	37%	-	Fix
CVE-2024-20337	High	8.2	30%	-	Fix
CVE-2021-39172	High	8.8	29%	-	Fix
CVE-2016-4975	Medium	6.1	20%	-	Fix

Common questions

How do I fix CVE-2026-1299?

Published advisories record a fix for 93 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-1299 being actively exploited?

Not that we know of. CVE-2026-1299 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.53% is the estimated probability that it will be exploited in the next 30 days. That is higher than 43% of all scored CVEs.

What does CVE-2026-1299 affect?

Published advisories record a fix for pypy3 (Debian), platform-python (Rocky), platform-python (Red Hat / RHEL), platform-python-debug (Rocky), and 89 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-1299

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-02-13.