VulnerabilityPublished 26 Oct 2026

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

Affects charm-toolsSource GCVE Database

Authoritative record:CVE-2026-113720· Medium 4.4

Not known to be exploited · CVSS 4.4 Medium.

Data as of 27 Oct 2026, 06:58 UTC

CVSS 4.0 base score

4.4Medium

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

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

Affected software

Product	Affected	Fixed in
Homebrewcharm-tools`pkg:brew/charm-tools`Other threats	Affected >=2.7.3	Fixed in–

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AI-suggested

A fix is available in virtualenv via PR #3425, which enforces copied files to have a fixed non-writable-by-others permission policy further restricted by the current umask. Users should upgrade to a version including this fix. No other mitigation is required if the environment is already patched. Restricting access to the environment and ensuring private parent directories can reduce exposure but do not fully mitigate the issue without the patch.

Description

A vulnerability in virtualenv's app-data copy seeder causes files copied from a cache to retain permissions from an older cache population, potentially resulting in files with broader access rights than intended. This occurs because shutil.copy preserves the cached file modes, overriding the current umask. An attacker with access to the new environment and a cache populated under permissive permissions can exploit this to modify files such as pip scripts.

Impact

Files copied from the cache into new virtualenv environments may have overly permissive file modes, allowing other local users with access to the environment to modify these files. This can lead to unauthorized code execution under the environment owner's privileges. The vulnerability does not allow forcing the owner's umask but exploits the cached file permissions. The impact is limited to local privilege escalation or code injection scenarios where multiple local accounts share access to the environment.

Summary

The virtualenv app-data seeder uses shutil.copy to copy files from a reusable cache into new environments. shutil.copy preserves the source file mode, which means that if the cache was populated under a permissive umask (e.g., 000), files copied into later environments can have overly broad permissions (e.g., mode 0666), even if the later environment uses a more restrictive umask (e.g., 022). This can allow other local accounts with access to the environment to modify files such as pip/__init__.py, potentially injecting code that runs with the environment owner's privileges. The vulnerability requires that the cache contains files created with broad permissions and that the new environment is accessible by other local accounts. The cache itself can remain private. The issue was reported by Anthropic's OSS Scanner and affects virtualenv versions starting from 20.0.2, with a fix introduced in PR #3425 that enforces a fixed non-writable-by-others policy on copied files.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Oct 2026, 06:58 UTC

Technical details

References

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