EUVD-2026-103040
GHSA-r2h8-g3f5-9cw2
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessReach CoAI download endpoint unauthenticated
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DeliveryCraft hash param with ../ sequences
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ExploitTraverse to target .tar.gz/.zip
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ExecutionDownload other users' archive
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ImpactDisclose sensitive archive contents
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V5 - File Handling Path canonicalization, traversal prevention
MITRE ATT&CK
2 techniques across 2 tactics: Discovery, Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | No special conditions - remote unauthenticated exploitation against default configurations of CoAI (Chat Nio) through 4.0.0, by injecting ../ sequences into the hash query parameter of the generation and article archive download endpoints. Exploitation is LIMITED by the fact that only files readable by the service process and matching the .tar.gz or .zip extension can be retrieved, so arbitrary-file disclosure is constrained to those archive types rather than any file on disk; impact is confidentiality-only with no write or code-execution capability. |
| Impact | Signals are consistent and point to a moderate, confidentiality-only issue. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms remote, unauthenticated, low-complexity exploitation with no user interaction, which is why the base score is a relatively high 6.9; however, impact is bounded to VC:L (limited confidentiality) with VI:N/VA:N, meaning no integrity or availability consequences and only partial information disclosure limited to readable .tar.gz/.zip archives. There is no CISA KEV listing and no explicit POC=YES flag in the input, so this is not confirmed as actively exploited; note that a detailed third-party technical write-up (hackmd) and VulnCheck advisory are referenced, which materially lower the bar for weaponization even though working exploit code is not confirmed. No EPSS score was provided, so widespread-exploitation probability cannot be quantified from this data. Net: a genuine but moderate priority - easy to exploit and unauthenticated, but limited to disclosure of specific archive file types in a niche self-hosted product, not a critical RCE. |
| Exploit ScenarioDerived | A remote, unauthenticated attacker sends a crafted request to the CoAI generation or article archive download endpoint with ../ sequences in the hash query parameter, directing it outside the intended archive directory. This lets them download other users' generated .tar.gz/.zip archives or other readable archive files on the host, disclosing their contents. A public technical write-up describing the flaw exists, lowering the effort required to reproduce it. |
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Alert meAnalysisAIv1 – Oct 16, 2026
Unauthenticated path traversal in CoAI (Chat Nio) through 4.0.0 lets remote attackers download arbitrary readable .tar.gz or .zip archives, including archives generated by other users, by injecting ../ sequences into the hash query parameter of the generation and article archive download endpoints. The flaw is remotely exploitable without credentials against default configurations (CVSS 4.0 vector PR:N, consistent with the assessed CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N), but the impact is confidentiality-only: only files readable by the service process and matching an archive extension can be retrieved, and there is no write or code-execution capability. No public exploit identified at time of analysis and no CISA KEV listing; the issue remains a moderate-severity information-disclosure risk on exposed instances.
RemediationAI
No vendor-released patch identified at time of analysis, so the priority is to reduce exposure while an upstream fix is produced. Because exploitation requires only the hash parameter of the generation and article archive download endpoints and does not require authentication, the most effective interim measure is to restrict reachability of those two routes: place them behind an authenticated reverse-proxy rule or IP allowlist, or temporarily disable the archive download feature if it is not business-critical. Note the trade-off: disabling or gating the endpoints breaks legitimate archive retrieval for all users. A code-level mitigation is to canonicalize the constructed path (for example filepath.Clean plus a check that the resolved absolute path remains under the intended archive base directory), reject any hash value containing path separators or dot-dot sequences, and enforce an ownership check so a requester can only download their own archives; the trade-off is that legitimate hashes containing unusual characters may need re-encoding. Additionally, run the application with a least-privilege service account and store generated archives outside the directories the service account can read, which limits the set of .tar.gz/.zip files that can be reached but requires reworking archive storage paths. Vendor points of contact should be monitored, and the advisories at https://www.vulncheck.com/advisories/coai-through-4.0.0-unauthenticated-path-traversal-via-archive-download-endpoints and https://hackmd.io/@hieuPenguinnn/coai-chatnio-generation-article-download-path-traversal consulted for updates.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The vulnerability is a classic CWE-22 improper limitation of a pathname to a restricted directory, present in the Go-based CoAI (Chat Nio) application. In the v4.0.0 source, the affected handlers live in addition/generation/api.go (lines 19-29) and addition/article/api.go (lines 25-35), where the user-supplied hash query parameter is used to construct the path of an archive that is then served back to the caller. Because the value is not canonicalized or constrained to an expected base directory, an attacker can supply ../ sequences to escape the intended archive store and reach sibling directories, including those holding other users' generated archives. Two factors bound the impact: the download path only returns files whose extension matches .tar.gz or .zip, so arbitrary-file disclosure is restricted to those archive types and to files the service account can read, and the resulting impact is confidentiality-only (no integrity or availability effect). The accompanying CPE entry (cpe:2.3:a:coaidev:coai:*:*:*:*:*:*:*:*) indicates all versions up to and including 4.0.0 are in scope.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Remote unauthenticated download with no interaction gives AV:N/AC:L/PR:N/UI:N; disclosure is limited to .tar.gz/.zip archives so C:L, with no integrity or availability impact.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
DescriptionCVE.org
CoAI (Chat Nio) through 4.0.0 contains an unauthenticated path traversal vulnerability in the generation and article archive download endpoints via the hash query parameter. Attackers can supply ../ sequences in hash to download any readable .tar.gz or .zip file, including other users' generated archives.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.
Exploit-DB