VulnerabilityPublished 27 Oct 2026

CVE-2026-113720: virtualenv · Seeded files retain permissions from an older cache

Affects hatchSource GCVE Database

Authoritative record:CVE-2026-113720· Medium 4.4

Not known to be exploited · CVSS 4.4 Medium : upgrade to 1.18.1_2 or 1.6.2 when convenient.

Data as of 27 Oct 2026, 23:27 UTC

CVSS 4.0 base score

4.4Medium

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

Patch: Available – fixed in 1.18.1_2, 1.6.2

CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

Attack Vector: Local
Attack Complexity: High
Attack Requirements: Present
Privileges Required: Low
User Interaction: Passive
Vulnerable system confidentiality: Low
Vulnerable system integrity: High
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Local: The vulnerable system 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 through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: High: The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques, for example, circumvention of address space randomization (ASLR) or data execution prevention (DEP) must be performed for the attack to be successful; Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system 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 Vulnerable System.
Vulnerable system integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the vulnerable system.
Vulnerable system 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 Vulnerable System 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 Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 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 hatch to 1.18.1_2 or 1.6.2.

Affected software

Product	Affected	Fixed in
Homebrewhatch`pkg:brew/hatch`Other threats	Affected >=1.2.0 <1.6.2 >=1.9.3 <1.18.1_2	Fixed in 1.6.2 1.18.1_2

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

AI-suggested

A patch is available and should be applied. The issue is fixed in virtualenv versions 1.6.2 and 1.18.1_2, which enforce non-writable-by-others permissions on copied files, further restricted by the current umask. Users should upgrade to these fixed versions to prevent permission leakage. No additional mitigation is required if the environment is already running a patched version.

Description

Virtualenv versions prior to 1.6.2 and 1.18.1_2 have a file permission issue where files copied from a cached app-data directory retain their original permissions, potentially allowing wider access than intended. This occurs because shutil.copy preserves cached file modes regardless of the current umask, leading to files with overly permissive modes in new environments. An attacker with access to the new environment and the ability to traverse it can exploit this to modify files such as pip/__init__.py, which then run with the environment owner's privileges.

Impact

Files in new virtualenv environments may have overly permissive permissions if the cache was created under a permissive umask, allowing other local users with access to the environment to modify executable files like pip scripts. This can lead to privilege escalation or unauthorized code execution under the environment owner's identity. The vulnerability requires that the attacker can traverse the environment directory and that the cache contains files with broad permissions. The cache itself remains private, so the attack vector depends on environment accessibility.

Summary

The vulnerability in virtualenv arises from the use of shutil.copy in the app-data seeder, which copies files from a reusable cache into new environments while preserving the cached file modes. If the cache was created under a permissive umask (e.g., 000), files copied later under a more restrictive umask (e.g., 022) still retain the broader permissions (e.g., 0666). This can allow other local accounts with access to the environment to modify files that should be protected, such as pip scripts, leading to code execution as the environment owner. The issue affects virtualenv versions starting from 20.0.2 and was fixed in versions 1.6.2 and 1.18.1_2 by enforcing stricter file permissions during copy operations.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Oct 2026, 23:27 UTC

Technical details

References

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