What’s Vulnerable › Vulnerabilities

CVE-2024-0397: Memory race condition in ssl.SSLContext certificate store methods

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-06-17 · updated 2026-06-17
• Weakness: CWE-362

Description

A defect was discovered in the Python “ssl” module where there is a memory race condition with the ssl.SSLContext methods “cert_store_stats()” and “get_ca_certs()”. The race condition can be triggered if the methods are called at the same time as certificates are loaded into the SSLContext, such as during the TLS handshake with a certificate directory configured. This issue is fixed in CPython 3.10.14, 3.11.9, 3.12.3, and 3.13.0a5.

Affected products

• Python Software Foundation Cpython: before 3.8.20; from 3.9.0 before 3.9.20; from 3.10.0 before 3.10.14; from 3.11.0 before 3.11.9; from 3.12.0 before 3.12.3; from 3.13.0a1 before 3.13.0a5 — fixed in 3.10.14, 3.11.9, 3.12.3, 3.13.0a5, 3.8.20, 3.9.20

How to fix

Upgrade to a fixed version: Python Software Foundation Cpython 3.10.14, 3.11.9, 3.12.3, 3.13.0a5. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2024/06/17/2
• https://github.com/python/cpython/commit/01c37f1d0714f5822d34063ca7180b595abf589d
• https://github.com/python/cpython/commit/29c97287d205bf2f410f4895ebce3f43b5160524
• https://github.com/python/cpython/commit/37324b421b72b7bc9934e27aba85d48d4773002e
• https://github.com/python/cpython/commit/542f3272f56f31ed04e74c40635a913fbc12d286
• https://github.com/python/cpython/commit/b228655c227b2ca298a8ffac44d14ce3d22f6faa
• https://github.com/python/cpython/commit/bce693111bff906ccf9281c22371331aaff766ab
• https://github.com/python/cpython/issues/114572
• https://github.com/python/cpython/pull/114573
• https://mail.python.org/archives/list/security-announce@python.org/thread/BMAK5BCGKYWNJOACVUSLUF6SFGBIM4VP/
• http://www.openwall.com/lists/oss-security/2024/06/17/2
• https://github.com/python/cpython/commit/01c37f1d0714f5822d34063ca7180b595abf589d

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