NVD / CVE Program· CNA mitre

CVE-2018-1000117: Python Software Foundation CPython version From 3.2 until 3.6.4 on Windows contains a Buffer Overflow vulnerability in os.symlink() function

Noroxi assessment

Priority: Monitor (action score 26/100)

Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 1% (FIRST EPSS); higher than 63.9% of all records.
Someone with local access to the system can trigger it. Administrator privileges are required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: n/a n/a 3.7.0.

Low priority for now. Upgrade to n/a n/a 3.7.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Python Software Foundation CPython version From 3.2 until 3.6.4 on Windows contains a Buffer Overflow vulnerability in os.symlink() function on Windows that can result in Arbitrary code execution, likely escalation of privilege. This attack appears to be exploitable via a python script that creates a symlink with an attacker controlled name or location. This vulnerability appears to have been fixed in 3.7.0 and 3.6.5.

MediumCVSS 6.7 · v3.1—Proof of concept Fix available

Published: Mar 7, 2018
Updated: Jun 16, 2026
EPSS: 1.0% · 63th percentile
CWE: CWE-120

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 26 / 40 · 6.7 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.0%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Proof of concept exists, no weaponized module
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
python	python	cpe:2.3:a:python:python
microsoft	windows	cpe:2.3:o:microsoft:windows

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

python python3.2.0 and later · before 3.4.9
python python3.5.0 and later · before 3.5.6
python python3.6.0 and later · before 3.6.5
python python3.7.0

Same product

python: all records

Other highest-scoring records for the same primary product.

CVE-2016-5636Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 all
47Plan
CVE-2007-4559Directory traversal vulnerability in the (1) extract and (2) extractall functions in the tarfile module in Python allows user-assisted remot
47Plan
CVE-2021-3177Python 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 Pyth
46Plan

Published before and after this one in the same product

← EarlierCVE-2018-1000030Feb 8, 2018 · Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free.
14Monitor
← EarlierCVE-2017-18207Mar 1, 2018 · The Wave_read._read_fmt_chunk function in Lib/wave.py in Python through 3.6.4 does not ensure a nonzero channel value, which allows attacker
26Monitor
Later →CVE-2018-1060Jun 18, 2018 · 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.
32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
n/a n/a	3.7.0 · description	Vendor (CNA)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Proof-of-concept repository on GitHub	stars:3	2018-06-05

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

PublishedMar 7, 2018
First PoCJun 5, 2018+90 d
TodayOct 31, 2026+3160 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

python/cpythonPR 5989

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
Administrator privileges are required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: High
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVSS vector

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

nvd-primary

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

The bug in code

The whole CWE-120 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

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Change log

Fix✗ → ✓Sep 29, 2026, 11:36 AM UTC

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References

bugs.python.org/issue33001

Show all references (1 more)

github.com/python/cpython/pull/5989

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records