Read the docs
TI-2021-02254 Aliases CVE-2021-3177GHSA-hc96-xw56-vfwh

Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c…

Priority HIGH 82CWE-120Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 12 fixed, 4 without a fix

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-120 and the CVSS impact.

Summary

Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Python applications that accept floating-point numbers as untrusted input, as demonstrated by a 1e300 argument to c_double.from_param. This occurs because sprintf is used unsafely.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.24002 97th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial Red Hat: 6 advisoriesRed Hat: 12 fixed, 4 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 12

CPEVersionsRoleVendor
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*3.6.0 – 3.6.12; 3.7.0 – 3.7.9; 3.8.0 – 3.8.7; 3.9.0 – 3.9.1Vulnerablepython-pillow
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*32VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*33VulnerableFedoraproject
cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*not specified by NVDVulnerableNetApp
cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*not specified by NVDVulnerableNetApp
cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*not specified by NVDVulnerableNetApp
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*9.0VulnerableDebian
cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:22.2.0:*:*:*:*:*:*:*22.2.0VulnerableOracle
cpe:2.3:a:oracle:communications_offline_mediation_controller:12.0.0.3.0:*:*:*:*:*:*:*12.0.0.3.0VulnerableOracle
cpe:2.3:a:oracle:communications_pricing_design_center:12.0.0.3.0:*:*:*:*:*:*:*12.0.0.3.0VulnerableOracle
  • cpe:2.3:a:python:python:*:*:*:*:*:*:*:* Versions 3.6.0 – 3.6.12; 3.7.0 – 3.7.9; 3.8.0 – 3.8.7; 3.9.0 – 3.9.1 Vulnerable ·python-pillow
  • cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
  • cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:* Versions not specified by NVD Vulnerable ·NetApp
  • cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:* Versions not specified by NVD Vulnerable ·NetApp
  • cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
  • cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:22.2.0:*:*:*:*:*:*:* Versions 22.2.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:communications_offline_mediation_controller:12.0.0.3.0:*:*:*:*:*:*:* Versions 12.0.0.3.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:communications_pricing_design_center:12.0.0.3.0:*:*:*:*:*:*:* Versions 12.0.0.3.0 Vulnerable ·Oracle
Show 2 more CPE
CPEVersionsRoleVendor
cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:*12.4.0.0VulnerableOracle
cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*8.8VulnerableOracle
  • cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:* Versions 12.4.0.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* Versions 8.8 Vulnerable ·Oracle

Remediation

Red Hat 6 advisories

  • RHSA-2022:5235 Released 2022-06-28 · Red Hat rating Moderate
    python security update
    • Red Hat Enterprise Linux Client (v. 7) python-2.7.5-92.el7_9, python-libs-2.7.5-92.el7_9
    • Red Hat Enterprise Linux Client Optional (v. 7) python-debug-2.7.5-92.el7_9, python-devel-2.7.5-92.el7_9, python-test-2.7.5-92.el7_9 +2
    • Red Hat Enterprise Linux ComputeNode Optional (v. 7) python-debug-2.7.5-92.el7_9, python-test-2.7.5-92.el7_9, python-tools-2.7.5-92.el7_9 +1
    • Red Hat Enterprise Linux Server (v. 7) python-2.7.5-92.el7_9, python-devel-2.7.5-92.el7_9, python-libs-2.7.5-92.el7_9 +1
    • Red Hat Enterprise Linux Server Optional (v. 7) python-debug-2.7.5-92.el7_9, python-test-2.7.5-92.el7_9, python-tools-2.7.5-92.el7_9 +1
    • Red Hat Enterprise Linux Workstation (v. 7) python-2.7.5-92.el7_9, python-devel-2.7.5-92.el7_9, python-libs-2.7.5-92.el7_9
    • Red Hat Enterprise Linux Workstation Optional (v. 7) python-debug-2.7.5-92.el7_9, python-test-2.7.5-92.el7_9, python-tools-2.7.5-92.el7_9 +1
  • RHSA-2021:3252 Released 2021-08-24 · Red Hat rating Moderate
    python27 security update
    • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) python27-babel-0.9.6-10.el7, python27-python-2.7.18-3.el7, python27-python-babel-0.9.6-10.el7 +8
    • Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) python27-babel-0.9.6-10.el7, python27-python-2.7.18-3.el7, python27-python-babel-0.9.6-10.el7 +8
    • Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) python27-babel-0.9.6-10.el7, python27-python-2.7.18-3.el7, python27-python-babel-0.9.6-10.el7 +8
  • RHSA-2021:3254 Released 2021-08-24 · Red Hat rating Moderate
    rh-python38 security, bug fix, and enhancement update
    • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
    • Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
    • Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
Show 3 more Red Hat advisories
  • RHSA-2021:1633 Released 2021-05-18 · Red Hat rating Moderate
    python3 security update
    • Red Hat Enterprise Linux AppStream (v. 8) platform-python-3.6.8-37.el8, platform-python-debug-3.6.8-37.el8, platform-python-devel-3.6.8-37.el8 +3
    • Red Hat Enterprise Linux BaseOS (v. 8) platform-python-3.6.8-37.el8, python3-3.6.8-37.el8, python3-libs-3.6.8-37.el8 +1
  • RHSA-2021:1879 Released 2021-05-18 · Red Hat rating Moderate
    python38:3.8 security update
    • Red Hat Enterprise Linux AppStream (v. 8) Cython-0.29.14-4.module+el8.4.0+8888+89bc7e79.src::python38:3.8, PyYAML-5.3.1-1.module+el8.4.0+8888+89bc7e79.src::python38:3.8, babel-2.7.0-10.module+el8.4.0+8888+89bc7e79.src::python38:3.8 +47
  • RHSA-2021:1761 Released 2021-05-18 · Red Hat rating Moderate
    python27:2.7 security and bug fix update
    • Red Hat Enterprise Linux AppStream (v. 8) Cython-0.28.1-7.module+el8.1.0+3111+de3f2d8e.src::python27:2.7, PyYAML-3.12-16.module+el8.1.0+3111+de3f2d8e.src::python27:2.7, babel-2.5.1-9.module+el8.1.0+3111+de3f2d8e.noarch::python27:2.7 +47

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 5AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 9AffectedNo fix yet
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2021:1633, RHSA-2021:1761, RHSA-2021:1879
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2021:1633
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2022:5235
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2022:5235
Red Hat Enterprise Linux ComputeNode Optional (v. 7)Fixed RHSA-2022:5235
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2022:5235
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2022:5235
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2022:5235
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2022:5235
Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:3252, RHSA-2021:3254
Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7)Fixed RHSA-2021:3252, RHSA-2021:3254
Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:3252, RHSA-2021:3254
Not affected: 2 products
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-3177
  2. 2026-10-03 Alias added: GHSA-hc96-xw56-vfwh

References

Exploit 1

Patch 6

Advisory 19

Other 2

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences