Buffer overread when using an empty list with SSLContext.set_npn_protocols()
Priority LOW 30Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · None · Low
- Fix status
- Partial Red Hat: 8 fixed, 3 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.
Summary
CPython 3.9 and earlier doesn't disallow configuring an empty list ("[]") for SSLContext.set_npn_protocols() which is an invalid value for the underlying OpenSSL API. This results in a buffer over-read when NPN is used (see CVE-2024-5535 for OpenSSL). This vulnerability is of low severity due to NPN being not widely used and specifying an empty list likely being uncommon in-practice (typically a protocol name would be configured).
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00744 55th percentileScored 2026-11-07
Fix Partial CPython (Python Software Foundation): 3.9.24, 3.10.0b1Red Hat: 5 advisoriesRed Hat: 8 fixed, 3 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Python Software Foundation | CPython | before 3.9.24; 3.10.0a1 to before 3.10.0b1 | 3.9.24, 3.10.0b1 | Patch available | CNA |
- CPython VendorPython Software Foundation Affected before 3.9.24; 3.10.0a1 to before 3.10.0b1 Fixed in 3.9.24, 3.10.0b1 Patch available CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:python:python:*:*:*:*:*:*:*:* | — | — | python-pillow |
- cpe:2.3:a:python:python:*:*:*:*:*:*:*:* Versions — — ·python-pillow
Remediation
- Fix · CNA CPython (Python Software Foundation) Fixed in 3.9.24, 3.10.0b1
Red Hat 5 advisories
- RHSA-2026:1652 Released 2026-02-02 · Red Hat rating ImportantRed Hat Ceph Storage
- Red Hat Ceph Storage 8 registry.redhat.io/rhceph/rhceph-8-rhel9
- RHSA-2026:0685 Released 2026-01-15 · Red Hat rating ModerateRed Hat Update Infrastructure 5 security update
- Red Hat Update Infrastructure 5 registry.redhat.io/rhui5/cds-rhel9, registry.redhat.io/rhui5/haproxy-rhel9, registry.redhat.io/rhui5/installer-rhel9 +1
- RHSA-2026:0414 Released 2026-01-08 · Red Hat rating ImportantA Subscription Management tool for finding and reporting Red Hat product usage
- Red Hat Discovery 2 registry.redhat.io/discovery/discovery-server-rhel9, registry.redhat.io/discovery/discovery-ui-rhel9
Show 2 more Red Hat advisories
- RHSA-2025:23342 Released 2025-12-18 · Red Hat rating Moderatepython3.9 security update
- Red Hat Enterprise Linux AppStream (v. 9) python-unversioned-command-3.9.25-2.el9_7, python3-devel-3.9.25-2.el9_7, python3-tkinter-3.9.25-2.el9_7
- Red Hat Enterprise Linux BaseOS (v. 9) python3-3.9.25-2.el9_7, python3-libs-3.9.25-2.el9_7, python3.9-3.9.25-2.el9_7
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) python3-3.9.25-2.el9_7, python3-debug-3.9.25-2.el9_7, python3-idle-3.9.25-2.el9_7 +2
- RHSA-2025:23530 Released 2025-12-18 · Red Hat rating Importantpython39:3.9 security update
- Red Hat Enterprise Linux AppStream (v. 8) PyYAML-5.4.1-1.module+el8.9.0+19644+d68f775d.src::python39:3.9, mod_wsgi-4.7.1-7.module+el8.10.0+23075+0aa18782.1.src::python39:3.9, numpy-1.19.4-3.module+el8.9.0+19644+d68f775d.src::python39:3.9 +47
- Red Hat Enterprise Linux CRB (v. 8) Cython-0.29.21-5.module+el8.9.0+19644+d68f775d.src::python39-devel:3.9, pybind11-2.7.1-1.module+el8.9.0+19644+d68f775d.src::python39-devel:3.9, pytest-6.0.2-2.module+el8.9.0+19644+d68f775d.src::python39-devel:3.9 +33
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 8 | Fixed | RHSA-2026:1652 |
| Red Hat Discovery 2 | Fixed | RHSA-2026:0414 |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2025:23530 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2025:23342 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2025:23342 |
| Red Hat Enterprise Linux CRB (v. 8) | Fixed | RHSA-2025:23530 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) | Fixed | RHSA-2025:23342 |
| Red Hat Update Infrastructure 5 | Fixed | RHSA-2026:0685 |
Not affected: 4 products
- Red Hat Ceph Storage 8
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2024-5642
- 2026-10-03 Alias added: GHSA-hrvr-7x5w-xpmq
References
Patch 2
Advisory 2
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Sources
- CVE-2024-5642 · CVE Program
- CVE-2024-5642 · NVD
- FIRST EPSS
- GHSA-hrvr-7x5w-xpmq · GitHub Advisory Database · CC BY 4.0
- CVE-2024-5642 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences