CVE-2025-6853VulnerabilityPublished 29 Jun 2025Updated 30 Jun 2025

CVE-2025-6853: Langchain-Chatchat · Path Traversal

Affects Langchain-ChatchatSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

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: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
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: 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: 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 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.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 29 Jun 2025
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 2026-10-25.

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 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
GitHubchatchat-space/Langchain-Chatchat`pkg:github/chatchat-space/Langchain-Chatchat`Other threats	Affected =0.3.0 =0.3.1	Fixed in–

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AI-suggested

Since no official patches are currently available, European organizations should implement the following specific mitigations: 1) Immediately audit and restrict access permissions on the server directories related to Langchain-Chatchat, ensuring the backend process runs with the least privilege necessary to limit file system exposure. 2) Implement web application firewall (WAF) rules to detect and block suspicious path traversal patterns in HTTP requests targeting the /knowledge_base/upload_temp_docs endpoint, particularly those manipulating the 'flag' parameter. 3) Conduct thorough input validation and sanitization on all user-supplied parameters, especially those controlling file paths, to prevent traversal sequences such as '../'. 4) Monitor logs for unusual access patterns or failed attempts to access unauthorized files, enabling early detection of exploitation attempts. 5) Isolate the Langchain-Chatchat backend service within a segmented network zone to contain potential breaches. 6) Prepare for rapid patch deployment by tracking vendor updates and subscribing to vulnerability advisories. 7) Consider temporary disabling or restricting the upload_temp_docs functionality if feasible until a patch is released. These targeted actions go beyond generic advice by focusing on immediate containment and detection strategies tailored to the vulnerability's characteristics.

Description

A vulnerability classified as critical has been found in chatchat-space Langchain-Chatchat up to 0.3.1. This affects the function upload_temp_docs of the file /knowledge_base/upload_temp_docs of the component Backend. The manipulation of the argument flag leads to path traversal. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used.

Impact

For European organizations using Langchain-Chatchat versions 0.3.0 or 0.3.1, this vulnerability poses a risk of unauthorized file access or modification on backend servers. This could lead to exposure of sensitive corporate or customer data, intellectual property theft, or disruption of services if critical files are overwritten. Organizations in sectors with strict data protection regulations, such as finance, healthcare, and government, could face compliance violations under GDPR if personal data is exposed. Additionally, attackers could leverage this vulnerability as a foothold for further lateral movement within the network, potentially escalating to more severe compromises. The remote and unauthenticated nature of the exploit increases the likelihood of scanning and automated attacks, which could result in widespread exploitation if not mitigated promptly. The medium severity rating suggests that while the vulnerability is serious, it may not directly lead to full system compromise without additional vulnerabilities or misconfigurations. However, the presence of a public exploit disclosure elevates the urgency for European organizations to assess and address this risk quickly.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Jun 2025, 07:54 UTC

Technical details

References

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