VulnerabilityPublished 26 Oct 2026

CVE-2026-113719: virtualenv · Seed replacement does not contain metadata deletion paths

Affects noxSource GCVE Database

Authoritative record:CVE-2026-113719· Medium 4.5

Not known to be exploited · CVSS 4.5 Medium : upgrade to 2026.10.20 or 2022.8.7_1 when convenient.

Data as of 27 Oct 2026, 06:43 UTC

CVSS 3.1 base score

4.5Medium

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 2026.10.20, 2022.8.7_1

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

Attack Vector: Local
Attack Complexity: High
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade nox to 2026.10.20 or 2022.8.7_1.

Affected software

Product	Affected	Fixed in
Homebrewnox`pkg:brew/nox`Other threats	Affected >=2021.10.1 <2022.8.7_1 >=2023.4.22_1 <2026.10.20	Fixed in 2022.8.7_1 2026.10.20

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

## Summary The app-data seeder joins paths from existing distribution metadata to site-packages and deletes the resulting paths without checking containment within the environment. Anthropic's OSS Scanner reported this as `ANT-2026-SXOEHWP7` in `virtualenv-20261015-005`, received on 15 October 2026. ## Affected area Removal of a previously installed seed package. ## Attacker-controlled input An environment being reused must contain distribution metadata influenced by another account. The invoking user must have deletion rights over the paths named by that metadata. Installing a new environment without existing package metadata does not enter this cleanup path. ## Affected code The relevant 21.14.8 source is in [seed uninstall](https://github.com/pypa/virtualenv/blob/a795ab116356afde11039cf2763d77e8a06da738/src/virtualenv/seed/embed/via_app_data/pip_install/base.py). ## Mechanism Before reinstalling a seed wheel, `PipInstall._uninstall_previous_version()` accepts an existing `pip-*.dist-info` directory in the destination. `_uninstall_dist()` reads its `top_level.txt` and `RECORD`, joins each entry to `site-packages`, and deletes the result. It does not check whether `..`, an absolute entry, or a linked parent takes the path outside the environment. The default app-data seeder reaches this path when it reuses a tree containing seed-package metadata; `--clear` removes that tree first. ## Reproduction and evidence The scanner prepared a project with `.venv/lib/python3.14/site-packages/pip-1.0.dist-info/`. Its `top_level.txt` contained `../../../../../Documents`; its `RECORD` named `../../../../../notes.txt,,`. The user's home initially held `Documents/thesis/chapter1.txt` and `notes.txt`. Running `virtualenv .venv` exited successfully but removed both paths. A control tree with `top_level.txt` set to `pip` and a normal `pip/__init__.py` RECORD entry left the home files in place. The reproducer prints `BUG` only when the control files survive and both attack targets disappear. The deletion uses the invoking user's permissions and runs during creation, before any use of the environment. It requires an existing destination that another account could populate; a fresh empty environment does not supply hostile metadata. The report traces this cleanup to #2186, first released in 20.8.1. [PR #3428](https://github.com/pypa/virtualenv/pull/3428) checks each deletion path against the resolved environment root and refuses to delete the root itself. ## Attack sequence ```mermaid sequenceDiagram participant A as Prepared .venv metadata participant V as App-data seeder participant P as site-packages participant H as User home A->>P: top_level.txt names ../../../../../Documents A->>P: RECORD names ../../../../../notes.txt V->>P: read pip-1.0.dist-info before reinstall P->>H: join entries without containment check V->>H: remove Documents and notes.txt V-->>A: virtualenv exits successfully ``` ## Reproducer files The following files are from the scanner report for `ANT-2026-SXOEHWP7`. They were tested against commit `a857a7823c73` in the scanner image. The `repro` entrypoint expects companion files under `/tmp/repro.d`; cases that change user IDs need a disposable root-capable container. The last output line is `BUG` when the reported behavior occurs. These files are included as evidence and were not rerun for this advisory update. **`repro`** ```text #!/usr/bin/env python3 import os import shutil import subprocess import sys from pathlib import Path work = Path("/tmp/repro-seed-uninstall") shutil.rmtree(work, ignore_errors=True) USER_FILES = ("Documents/thesis/chapter1.txt", "notes.txt") def make_home(name): home = work / name (home / "Documents" / "thesis").mkdir(parents=True) (home / "Documents" / "thesis" / "chapter1.txt").write_text("months of work\n") (home / "notes.txt").write_text("my notes\n") return home def unpack_attacker_project(home, top_level_line, record_line): subprocess.run( [sys.executable, "/tmp/repro.d/make_project_tree.py", home / "project", top_level_line, record_line], check=True, ) def user_runs_virtualenv(home): # HOME only gives each run its own ~ and app-data; --no-periodic-update keeps the run offline result = subprocess.run( ["virtualenv", "--no-periodic-update", ".venv"], cwd=home / "project", env={**os.environ, "HOME": str(home)}, stdout=subprocess.PIPE, text=True, check=True, ) print(result.stdout, end="") def files_left(home): return [f for f in USER_FILES if (home / f).exists()] # control: the project ships well-formed pip metadata control_home = make_home("control") unpack_attacker_project(control_home, "pip", "pip/__init__.py,,") user_runs_virtualenv(control_home) control_left = files_left(control_home) print(f"CONTROL user files still in ~ after virtualenv: {control_left}") # attack: site-packages is ~/project

References

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