CVE-2026-112934VulnerabilityPublished 29 Oct 2026

lexicon · filelock: SoftReadWriteLock holder refresh writes through a hard link and hangs on a named pipe that another local

Affects lexiconSource GCVE Database

Compare

Authoritative record:CVE-2026-112934· Medium 6.1

Not known to be exploited · CVSS 6.1 Medium : upgrade to 3.25.2_5 when convenient.

Data as of 30 Oct 2026, 07:32 UTC

CVSS 3.1 base score

6.1Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	6.1

Patch: Available – fixed in 3.25.2_5

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

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

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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: 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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

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 29 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.
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

Upgrade lexicon to 3.25.2_5.

Affected software

Product	Affected	Fixed in
Homebrewlexicon`pkg:brew/lexicon`Other threats	Affected >=3.25.2_3 <3.25.2_5	Fixed in 3.25.2_5

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 by upgrading filelock to version 3.25.2_5 or later. This fixes the issue with holder record refresh writes through hard links and hanging on FIFOs. No other mitigation is indicated or required by the vendor advisory.

Description

A vulnerability in filelock versions 4.0.0 through 4.2.0 allows a local user who owns the lock's .rw directory tree to interfere with the SoftReadWriteLock holder refresh mechanism. This can cause the lock user's process to hang when writing to a named pipe (FIFO) or overwrite part of its own private file via a hard link under certain kernel configurations. The issue leads to a denial of service by stalling lock acquisition and heartbeat threads, allowing multiple processes to believe they hold the write lock simultaneously. The vulnerability requires local access and specific filesystem conditions, such as permissive hard-link policies or ownership of the lock directory in a sticky or writable directory. A fix is available in version 3.25.2_5.

Impact

The vulnerability allows a local user with write access to the lock's .rw directory to cause denial of service by hanging the lock user's write_lock() or read_lock() calls when a FIFO is involved, preventing heartbeat refresh and causing lock state corruption. Additionally, on systems with permissive hard-link policies, the lock user's private files can be partially overwritten with holder record data, causing low integrity impact. There is no confidentiality impact. The availability impact is high as the lock can be held indefinitely by a compromised state, and two processes may simultaneously believe they hold the write lock.

Summary

The SoftReadWriteLock and AsyncSoftReadWriteLock in filelock refresh their holder records by reopening and writing to a file under <path>.rw/holders/. This operation uses a blocking open with O_WRONLY | O_NOFOLLOW flags but does not verify the opened file type beyond symbolic links. A local user owning the lock's .rw directory can rename a FIFO or hard link over the holder record file. Opening a FIFO causes the lock user's write operation to hang indefinitely, blocking heartbeat threads and allowing lock state corruption where two processes believe they hold the lock. On kernels permitting hard links to files not owned by the caller (e.g., Linux with fs.protected_hardlinks=0), the lock user overwrites the first ~135 bytes of one of its private files with the holder record. The vulnerability affects filelock versions >=4.0.0 and <=4.2.0 and is rated medium severity with CVSS 6.1. The issue requires local user privileges and specific filesystem conditions. The vulnerability is fixed in version 3.25.2_5.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 07:32 UTC

Technical details

References

Community reviews

Related threats