CVE-2026-112906VulnerabilityPublished 9 Nov 2026

gam · filelock: SoftFileLock evicts a fresh lock file whose watched age another local user's pre-dated file passed on

Affects gamSource GCVE Database

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Authoritative record:CVE-2026-112906· Medium 4.7

Not known to be exploited · CVSS 4.7 Medium · fixed in 4.2.0 : update gam when convenient.

Data as of 9 Nov 2026, 20:05 UTC

CVSS 3.1 base score

4.7Medium

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

Patch: Available – fixed in 4.2.0

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

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

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: None: There is no loss of confidentiality within the impacted component.
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 impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within 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
Weaponized: 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 9 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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
Homebrewgam`pkg:brew/gam`Other threats	Affected >=7.50.00	Fixed in–

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AI-suggested

A fix is available in versions later than 4.2.0 of filelock. Users should upgrade to a fixed version beyond 4.2.0. The vulnerability only affects filesystems that reuse inode numbers immediately (ext4 and overlayfs on ext4) and directories where an unprivileged user can create files. Restricting write permissions on lock directories and their ancestors or using filesystems that do not reuse inode numbers immediately can reduce risk.

Description

A vulnerability in filelock versions 4.1.0 through 4.2.0 allows a local unprivileged user to cause a lock eviction by exploiting inode reuse and coarse clock timestamp manipulation on ext4 or overlayfs filesystems. This results in two processes of the lock owner entering a critical section simultaneously, violating lock integrity without affecting confidentiality or availability. The attack requires specific timing conditions and filesystem behavior, making exploitation complex and unreliable.

Impact

The vulnerability impacts integrity by allowing two processes of the lock owner to simultaneously hold what should be an exclusive lock, potentially causing concurrent writes to protected data without detection. There is no impact on confidentiality or availability. Exploitation requires local access with low privileges and high attack complexity due to timing and filesystem constraints.

Summary

The filelock library's SoftFileLock and MarkerSoftFileLock mechanisms evict a lock file if it remains unchanged for two seconds, based on modification time and inode number. A local attacker who can create files in the lock directory (including sticky /tmp) can create a file with a future timestamp and unlink it at a precise time. On filesystems like ext4 that immediately reuse freed inode numbers, the lock owner's next lock file inherits the inode and timestamp, causing the lock to be mistakenly evicted. This allows two lock owner processes to enter the critical section simultaneously, breaking lock integrity. The vulnerability requires ext4-style inode reuse, predictable coarse clock timestamps, and precise timing, resulting in a medium-severity integrity impact without confidentiality or availability loss.

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What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Nov 2026, 20:05 UTC

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