VulnerabilityPublished 4 Nov 2026

CVE-2026-121938: moyangzhan langchain4j-aideepin · Insecure Direct Object Reference

Affects moyangzhan langchain4j-aideepinSource CVE Database V5

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Not known to be exploited · CVSS 6.0 Medium : upgrade to 3.31.0 when convenient.

Data as of 4 Nov 2026, 12:59 UTC

CVSS 4.0 base score

6.0Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (VulnCheck)	CVSS 4.0	6.0
CNA (VulnCheck)	CVSS 3.1	5.3

Patch: Available – fixed in 3.31.0

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

Attack Vector: Network
Attack Complexity: High
Attack Requirements: Present
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
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: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
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: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within 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 4 Nov 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 4 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

Upgrade moyangzhan langchain4j-aideepin to 3.31.0.

Affected software

Product	Affected	Fixed in
moyangzhanlangchain4j-aideepin	Affected <3.31.0	Fixed in 3.31.0
GitHublangchain4j-aideepin`pkg:github/langchain4j-aideepin`Other threats	Affected <3.31.0	Fixed in 3.31.0

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AI-suggested

Upgrade langchain4j-aideepin to version 3.31.0 or later, where the authorization bypass vulnerability has been fixed. No other mitigations are indicated by the vendor advisory.

Description

langchain4j-aideepin versions before 3.31.0 have an authorization bypass vulnerability allowing authenticated users to access other users' character-chat conversations by specifying their character UUID. This flaw occurs because the CharacterService.detail endpoint does not verify ownership before returning sensitive data such as questions, AI responses, and media URLs.

Impact

An attacker with authenticated access can read sensitive conversation data of other users, potentially exposing private questions, AI-generated answers, and media attachments. This compromises user privacy and confidentiality within the application. There is no indication of remote code execution or privilege escalation beyond data disclosure.

Summary

CVE-2026-121938 is an insecure direct object reference vulnerability in langchain4j-aideepin prior to version 3.31.0. Authenticated users can exploit this by sending a GET request to /character/{uuid} with another user's character UUID. The CharacterService.detail method fails to perform an ownership check, enabling unauthorized access to the victim's chat conversations, including questions, AI-generated answers, and associated attachments and audio URLs. This vulnerability was fixed in version 3.31.0.

References

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