Is CVE-2021-3177 in the CISA KEV catalog?

No. CVE-2021-3177 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3177?

CVE-2021-3177 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2021-3177?

CVE-2021-3177 has an EPSS score of 18.85% (97th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3177?

Upgrade python2.7 on debian 11 to 2.7.18-2 or later. Fixes are available for 21 affected products.

CVE & CISA-KEV Catalog

CVE-2021-3177

CRITICALEPSS 97th pctl

9.8

CVSS v3

NVD

Description

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.

CWE-120Classic Buffer Overflow

How to fix

Remediation Available

python2.7Debian

Fixed in:2.7.18-2CVE-2021-3177

python2.7Ubuntu

Fixed in:2.7.6-8ubuntu0.6+esm8USN-4754-1

Fixed in:2.7.6-8ubuntu0.6+esm10USN-4754-5

Fixed in:2.7.12-1ubuntu0~16.04.18USN-4754-4

Fixed in:2.7.12-1ubuntu0~16.04.14USN-4754-1

Fixed in:2.7.17-1~18.04ubuntu1.6USN-4754-4

Fixed in:2.7.17-1~18.04ubuntu1.3USN-4754-1

Fixed in:2.7.18-1~20.04.1USN-4754-3

python2.7-minimalUbuntu

Fixed in:2.7.6-8ubuntu0.6+esm10USN-4754-5

Fixed in:2.7.6-8ubuntu0.6+esm8USN-4754-1

Fixed in:2.7.12-1ubuntu0~16.04.14USN-4754-1

Fixed in:2.7.12-1ubuntu0~16.04.18USN-4754-4

Fixed in:2.7.17-1~18.04ubuntu1.3USN-4754-1

Fixed in:2.7.17-1~18.04ubuntu1.6USN-4754-4

Fixed in:2.7.18-1~20.04.1USN-4754-3

python3.10Ubuntu

Fixed in:3.10.12-1~22.04.4USN-6891-1

python3.10-minimalUbuntu

Fixed in:3.10.12-1~22.04.4USN-6891-1

python3.11Ubuntu

Fixed in:3.11.0~rc1-1~22.04.1~esm1USN-6891-1

Fixed in:3.11.6-3ubuntu0.1USN-6891-1

python3.11-minimalUbuntu

Fixed in:3.11.0~rc1-1~22.04.1~esm1USN-6891-1

Fixed in:3.11.6-3ubuntu0.1USN-6891-1

python3.12Ubuntu

Fixed in:3.12.0-1ubuntu0.1USN-6891-1

python3.12-minimalUbuntu

Fixed in:3.12.0-1ubuntu0.1USN-6891-1

python3.4Ubuntu

Fixed in:3.4.3-1ubuntu1~14.04.7+esm10USN-4754-1

python3.4-minimalUbuntu

Fixed in:3.4.3-1ubuntu1~14.04.7+esm10USN-4754-1

python3.5Ubuntu

Fixed in:3.5.2-2ubuntu0~16.04.4~14.04.1+esm1USN-6891-1

Fixed in:3.5.2-2ubuntu0~16.04.13+esm13USN-6891-1

Fixed in:3.5.2-2ubuntu0~16.04.13USN-4754-1

python3.5-minimalUbuntu

Fixed in:3.5.2-2ubuntu0~16.04.4~14.04.1+esm1USN-6891-1

Fixed in:3.5.2-2ubuntu0~16.04.13USN-4754-1

Fixed in:3.5.2-2ubuntu0~16.04.13+esm13USN-6891-1

python3.6Ubuntu

Fixed in:3.6.9-1~18.04ubuntu1.4USN-4754-1

Fixed in:3.6.9-1~18.04ubuntu1.13+esm2USN-6891-1

python3.6-minimalUbuntu

Fixed in:3.6.9-1~18.04ubuntu1.4USN-4754-1

Fixed in:3.6.9-1~18.04ubuntu1.13+esm2USN-6891-1

python3.7Ubuntu

Fixed in:3.7.5-2~18.04.4USN-4754-3

Fixed in:3.7.5-2ubuntu1~18.04.2+esm3USN-6891-1

python3.7-minimalUbuntu

Fixed in:3.7.5-2ubuntu1~18.04.2+esm3USN-6891-1

Fixed in:3.7.5-2~18.04.4USN-4754-3

python3.8Ubuntu

Fixed in:3.8.0-3~18.04.1USN-4754-3

Fixed in:3.8.0-3ubuntu1~18.04.2+esm2USN-6891-1

Fixed in:3.8.10-0ubuntu1~20.04.10USN-6891-1

Fixed in:3.8.5-1~20.04.2USN-4754-1

python3.8-minimalUbuntu

Fixed in:3.8.0-3ubuntu1~18.04.2+esm2USN-6891-1

Fixed in:3.8.0-3~18.04.1USN-4754-3

Fixed in:3.8.10-0ubuntu1~20.04.10USN-6891-1

Fixed in:3.8.5-1~20.04.2USN-4754-1

python3.9Ubuntu

Fixed in:3.9.5-3ubuntu0~20.04.1+esm2USN-6891-1

python3.9-minimalUbuntu

Fixed in:3.9.5-3ubuntu0~20.04.1+esm2USN-6891-1

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 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

18.85%probability of exploitation in 30 days

97thpercentile

Very high risk: more likely to be exploited than 97% of all known CVEs.

References

Related Vulnerabilities

Other CWE-120 (Classic Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0195	Medium	6.8	100%	-	Fix
CVE-2017-7269	Critical	9.8	100%	KEV	-
CVE-2019-11043	High	8.7	99%	KEV + Ransom	Fix
CVE-2011-4862	High	10.0	95%	-	Fix
CVE-2007-5659	High	7.8	94%	KEV	Fix
CVE-2022-3786	High	7.5	92%	-	Fix

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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 2025-12-18.