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CVE-2021-29921

python-ipaddress: Improper input validation of octal strings

In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

CVSS 3.1 · 9.8 Critical EPSS 6.8% KEV · Not listed
Vendors
Oracle Python Redhat
Products
Communications Cloud Native Core Automated Test Suite Communications Cloud Native Core Binding Support Function Communications Cloud Native Core Network Slice Selection Function and 5 more
CVE-2018-1060

python: DOS via regular expression catastrophic backtracking in apop() method in pop3lib

python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in pop3lib's apop() method. An attacker could use this flaw to cause denial of service.

CVSS 3.1 · 7.5 High EPSS 5.0% KEV · Not listed
Vendors
Canonical Debian Fedoraproject and 2 more
Products
Ubuntu Linux Debian Linux Fedora and 11 more
CVE-2018-1000802

python: Command injection in the shutil module

Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection') vulnerability in shutil module (make_archive function) that can result in Denial of service, Information gain via injection of arbitrary files on the system or entire drive. This attack appear to be exploitable via Passage of unfiltered user input to the function. This vulnerability appears to have been fixed in after commit add531a1e55b0a739b0f42582f1c9747e5649ace.

CVSS 3.1 · 9.8 Critical EPSS 20.1% KEV · Not listed
Vendors
Canonical Debian Opensuse and 1 more
Products
Ubuntu Linux Debian Linux Leap and 1 more
CVE-2018-1000030

python: Heap-Buffer-Overflow and Heap-Use-After-Free in Objects/fileobject.c

Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory. The PSRT has stated that this is not a security vulnerability due to the fact that the attacker must be able to run code, however in some situations, such as function as a service, this vulnerability can potentially be used by an attacker to violate a trust boundary, as such the DWF feels this issue deserves a CVE.

CVSS 3.1 · 3.6 Low EPSS 1.2% KEV · Not listed
Vendors
Canonical Python
Products
Ubuntu Linux Python
CVE-2017-9233

expat: Inifinite loop due to invalid XML in external entity

XML External Entity vulnerability in libexpat 2.2.0 and earlier (Expat XML Parser Library) allows attackers to put the parser in an infinite loop using a malformed external entity definition from an external DTD.

CVSS 3.1 · 7.5 High EPSS 8.7% KEV · Not listed
Vendors
Debian Libexpat Project Python
Products
Debian Linux Libexpat Python
CVE-2017-1000158

python: Integer overflow in PyString_DecodeEscape results in heap-base buffer overflow

CPython (aka Python) up to 2.7.13 is vulnerable to an integer overflow in the PyString_DecodeEscape function in stringobject.c, resulting in heap-based buffer overflow (and possible arbitrary code execution)

CVSS 3.1 · 9.8 Critical EPSS 7.9% KEV · Not listed
Vendors
Debian Python
Products
Debian Linux Python
CVE-2016-9063

firefox: Possible integer overflow to fix inside XML_Parse in Expat

An integer overflow during the parsing of XML using the Expat library. This vulnerability affects Firefox < 50.

CVSS 3.1 · 9.8 Critical EPSS 5.4% KEV · Not listed
Vendors
Debian Mozilla Python
Products
Debian Linux Firefox Python
CVE-2016-4472

expat: Undefined behavior and pointer overflows

The overflow protection in Expat is removed by compilers with certain optimization settings, which allows remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via crafted XML data. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-1283 and CVE-2015-2716.

CVSS 3.1 · 8.1 High EPSS 11.9% KEV · Not listed
Vendors
Canonical Libexpat Project Mcafee and 1 more
Products
Ubuntu Linux Libexpat Policy Auditor and 1 more
CVE-2016-0718

expat: Out-of-bounds heap read on crafted input causing crash

Expat allows context-dependent attackers to cause a denial of service (crash) or possibly execute arbitrary code via a malformed input document, which triggers a buffer overflow.

CVSS 3.1 · 9.8 Critical EPSS 13.3% KEV · Not listed
Vendors
Apple Canonical Debian and 7 more
Products
Mac Os X Ubuntu Linux Debian Linux and 13 more
CVE-2019-5010

python: NULL pointer dereference using a specially crafted X509 certificate

An exploitable denial-of-service vulnerability exists in the X509 certificate parser of Python.org Python 2.7.11 / 3.6.6. A specially crafted X509 certificate can cause a NULL pointer dereference, resulting in a denial of service. An attacker can initiate or accept TLS connections using crafted certificates to trigger this vulnerability.

CVSS 3.1 · 7.5 High EPSS 20.7% KEV · Not listed
Vendors
Debian Opensuse Python and 1 more
Products
Debian Linux Leap Python and 6 more
CVE-2019-16935

python: XSS vulnerability in the documentation XML-RPC server in server_title field

The documentation XML-RPC server in Python through 2.7.16, 3.x through 3.6.9, and 3.7.x through 3.7.4 has XSS via the server_title field. This occurs in Lib/DocXMLRPCServer.py in Python 2.x, and in Lib/xmlrpc/server.py in Python 3.x. If set_server_title is called with untrusted input, arbitrary JavaScript can be delivered to clients that visit the http URL for this server.

CVSS 3.1 · 6.1 Medium EPSS 4.7% KEV · Not listed
Vendors
Canonical Debian Python and 1 more
Products
Ubuntu Linux Debian Linux Python and 3 more
CVE-2018-20852

python: Cookie domain check returns incorrect results

http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname as a suffix (e.g., pythonicexample.com to steal cookies for example.com). When a program uses http.cookiejar.DefaultPolicy and tries to do an HTTP connection to an attacker-controlled server, existing cookies can be leaked to the attacker. This affects 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3.

CVSS 3.1 · 4.3 Medium EPSS 3.7% KEV · Not listed
Vendors
Python Redhat
Products
Python Ansible Tower Enterprise Linux and 1 more
CVE-2018-14647

python: Missing salt initialization in _elementtree.c module

Python's elementtree C accelerator failed to initialise Expat's hash salt during initialization. This could make it easy to conduct denial of service attacks against Expat by constructing an XML document that would cause pathological hash collisions in Expat's internal data structures, consuming large amounts CPU and RAM. The vulnerability exists in Python versions 3.7.0, 3.6.0 through 3.6.6, 3.5.0 through 3.5.6, 3.4.0 through 3.4.9, 2.7.0 through 2.7.15.

CVSS 3.1 · 7.5 High EPSS 10.9% KEV · Not listed
Vendors
Canonical Debian Fedoraproject and 3 more
Products
Ubuntu Linux Debian Linux Fedora and 12 more
CVE-2026-0864

Configuration Injection via Carriage Return (\r) in write() method

When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.

CVSS 4.0 · 4.1 Medium EPSS < 1% KEV · Not listed
Vendors
Python
Products
Cpython Python
CVE-2026-7210

The expat and elementtree parsers use insufficient entropy for XML hash-flooding protection

`xml.parsers.expat` and `xml.etree.ElementTree` use insufficient entropy for Expat hash-flooding protection, which allows a crafted XML document to trigger hash flooding.\r\n\r\nFully mitigating this vulnerability requires both updating libexpat to 2.8.0 or later and applying this patch.

CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Vendors
Python
Products
Cpython Python
CVE-2026-3087

shutil.unpack_archive() doesn't check for Windows absolute paths in ZIPs

If `shutil.unpack_archive()` is given a ZIP archive with an absolute Windows path containing a drive (`C:\\...`) then the archive will be extracted outside the target directory which is different than other operating systems. Only Windows is affected by this vulnerability.

CVSS 4.0 · 6 Medium EPSS < 1% KEV · Not listed
Vendors
Microsoft Python
Products
Windows Cpython Python
CVE-2026-3644

Incomplete control character validation in http.cookies

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

CVSS 4.0 · 6 Medium EPSS < 1% KEV · Not listed
Vendors
Python
Products
Cpython Python
CVE-2026-4224

Stack overflow parsing XML with deeply nested DTD content models

When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.

CVSS 4.0 · 6 Medium EPSS < 1% KEV · Not listed
Vendors
Python
Products
Cpython Python
CVE-2026-4360

Tarfile.extract() doesn't fully respect filter parameter

In the Tarfile.extract() function, the filter parameter is not passed properly when extracting hardlinks. An affected system that extracts content from untrusted tar files could end up writing files with an unexpected uid/gid despite the user passing filter='data' to the extract() function.

CVSS 4.0 · 2 Low EPSS < 1% KEV · Not listed
Vendors
Python
Products
Cpython Python