CVE-2026-1502: HTTP client proxy tunnel headers not validated for CR/LF

Published Apr 10, 2026
·
Updated

CR/LF bytes were not rejected by HTTP client proxy tunnel headers or host.

Other sources

HTTP client proxy tunnel headers not validated for CR/LF

— Microsoft

Affected Software

13 affected componentsFixes available
Python Software Foundation CPython
Microsoft azl3 python3 3.12.9-10
Patch available
Microsoft azl3 python3 3.12.9-11
Patch available
debian/pypy3*
debian/pypy3*
debian/pypy3<7.3.22+dfsg-1
7.3.22+dfsg-1
debian/python3.11<3.11.2-6+deb12u9
3.11.2-6+deb12u9
debian/python3.13<3.13.5-2+deb13u3
3.13.5-2+deb13u3
debian/python3.14<3.14.5-1
3.14.5-1
debian/pypy3<=7.3.11+dfsg-2+deb12u3, <=7.3.19+dfsg-2
8.0.1+dfsg-1
debian/python3.11<=3.11.2-6+deb12u8
3.11.2-6+deb12u9
debian/python3.13
3.13.5-2+deb13u53.13.18-1
debian/python3.14
3.14.10-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade debian/pypy3 to a version that resolves this vulnerability.

    Fixed in 7.3.22+dfsg-1
  2. Upgrade

    Upgrade debian/python3.11 to a version that resolves this vulnerability.

    Fixed in 3.11.2-6+deb12u9
  3. Upgrade

    Upgrade debian/python3.13 to a version that resolves this vulnerability.

    Fixed in 3.13.5-2+deb13u3
  4. Upgrade

    Upgrade debian/python3.14 to a version that resolves this vulnerability.

    Fixed in 3.14.5-1
  5. Upgrade

    Upgrade debian/pypy3 to a version that resolves this vulnerability.

    Fixed in 8.0.1+dfsg-1
  6. Upgrade

    Upgrade debian/python3.13 to a version that resolves this vulnerability.

    Fixed in 3.13.5-2+deb13u5Fixed in 3.13.18-1
  7. Upgrade

    Upgrade debian/python3.14 to a version that resolves this vulnerability.

    Fixed in 3.14.10-1

Event History

Apr 10, 2026
CVE Published
via MITRE·05:54 PM
Data Sourced
via MITRE·05:54 PM
Description
Data Sourced
via OSV·05:54 PM
DescriptionSeverity
Data Sourced
via NVD·06:16 PM
DescriptionSeverityWeakness
Data Sourced
via OSV·06:16 PM
Affected Software
Data Sourced
via Red Hat·07:01 PM
DescriptionSeverityAffected Software
Apr 15, 2026
Data Sourced
via Microsoft·08:04 AM
DescriptionSeverityWeaknessAffected Software

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What is the severity of CVE-2026-1502?

The severity of CVE-2026-1502 is rated as medium with a CVSS score of 5.7.

2

How do I fix CVE-2026-1502?

To fix CVE-2026-1502, ensure that the HTTP client proxy tunnel headers validate CR/LF sequences properly.

3

What vulnerability type is CVE-2026-1502 classified as?

CVE-2026-1502 is classified as a CRLF Injection vulnerability.

4

Which software is affected by CVE-2026-1502?

CVE-2026-1502 affects various versions of CPython from the Python Software Foundation and Microsoft azl3 Python 3.

5

What are the risks associated with CVE-2026-1502?

The risks associated with CVE-2026-1502 include potential HTTP response splitting and malicious data manipulation through improper validation.

Company

Resources

Contact

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