CVE-2021-3177
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…
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 24.0%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 24.00% probability · 98th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-120
- Affected
- python/python · fedoraproject/fedora · netapp/active iq unified manager · netapp/ontap select deploy administration utility · debian/debian linux · oracle/communications cloud native core network function cloud native environment · oracle/communications offline mediation controller · oracle/communications pricing design center · oracle/enterprise manager ops center · oracle/zfs storage appliance kit
- Source
- cve@mitre.org
EPSS 24.0% since 3 November 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugs.python.org/issue42938Exploit, Issue Tracking, Patch, Vendor Advisory
- https://github.com/python/cpython/pull/24239Patch, Third Party Advisory
- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2021/04/msg00005.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/02/msg00013.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BRHOCQYX3QLDGDQGTWQAUUT2GGIZCZUO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCFZMVRQUKCBQIG5F2CBVADK63NFSE4A/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FPE7SMXYUIWPOIZV4DQYXODRXMFX3C5E/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MGSV6BJQLRQ6RKVUXK7JGU7TP4QFGQXC/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NODWHDIFBQE5RU5PUWUVE47JOT5VCMJ2/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NQPARTLNSFQVMMQHPNBFOCOZOO3TMQNA/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NXSMBHES3ANXXS2RSO5G6Q24BR4B2PWK/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/V6XJAULOS5JVB2L67NCKKMJ5NTKZJBSD/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y4KSYYWMGAKOA2JVCQA422OINT6CKQ7O/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YDTZVGSXQ7HR7OCGSUHTRNTMBG43OMKU/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7GZV74KM72O2PEJN2C4XP3V5Q5MZUOO/
- https://news.ycombinator.com/item?id=26185005Third Party Advisory
- https://python-security.readthedocs.io/vuln/ctypes-buffer-overflow-pycarg_repr.htmlPatch, Third Party Advisory
- https://security.gentoo.org/glsa/202101-18Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210226-0003/Third Party Advisory
- https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory
- https://bugs.python.org/issue42938Exploit, Issue Tracking, Patch, Vendor Advisory
- https://github.com/python/cpython/pull/24239Patch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.