Medium Input validation exploit reference

CVE-2025-66451 — LibreChat's Improper Input Validation in Prompt Creation API Enables Unauthorized Permission Changes

LibreChat is a ChatGPT clone with additional features. In versions 0.8.0 and below, when creating prompts, JSON requests are sent to define and modify the prompts via PATCH endpoint for prompt groups (/api/prompts/groups/:groupId). However, the request bodies are not sufficiently validated for proper input, enabling users to modify prompts in a way that was not intended as part of the front end system. The patchPromptGroup function passes req.body directly to updatePromptGroup() without filtering sensitive fields. This issue is fixed in version 0.8.1.

Published Dec 11, 2025 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+4
Technical severity (medium)+3
CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.33%

ahead of 25% of scored CVEs · Oct 14, 2026

Affects

Danny-avila

Danny-avila/librechat and 1 more

CVSS base

6.5

Medium · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Danny-avila Danny-avila/librechat, Librechat Librechat).
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (input validation), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Danny-avila	Danny-avila/librechat	version < 0.8.1	Vulnerable	CVE Program (cve.org) e CISA ADP
Librechat	Librechat	< 0.8.1	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.3	CVSS 4.0	Medium	—	—	security-advisories@github.com via NIST National Vulnerability Database
5.3	CVSS 4.0	Medium	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
6.5	CVSS 3.1	Medium	2.8	3.6	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-20 · Improper Input Validation

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.33%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · danny-avila/librechat
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 6.5
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
2025
CVE published
Dec 11, 2025 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

2 on the record

github.com/danny-avila/LibreChat/security/advisories/GHSA-vpqq-5qr4-655h
Exploit, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/danny-avila/LibreChat/commit/01413eea3d3c1454d32ca9704fa9640407839737
Patch, x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

Danny-avila
every CVE for this vendor

Input validation
same class

CWE-20
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-54040 LibreChat: 2FA Backup Code Regeneration Without OTP Verification Allows 2FA Bypass Jun 25, 2026
Medium CVE-2026-54037 LibreChat: Incomplete Fix for CVE-2025-7105 — /api/convos/duplicate Lacks Rate Limiting Applied to /api/convos/fork Jun 25, 2026
Medium CVE-2026-54027 LibreChat: Image Upload Route Bypasses Agent Permission Check — Incomplete Fix for File Upload Authorization Jun 25, 2026
Medium CVE-2026-54029 LibreChat: IDOR in Message Deletion — Incomplete Fix for CVE-2024-41703 Leaves deleteMessages() Without User Filter Jun 25, 2026
Medium CVE-2026-54025 LibreChat: Stored XSS via unescaped image alt text in markdown artifact preview Jun 25, 2026
Medium CVE-2026-54024 LibreChat: Incomplete Fix for CVE-2024-11171 — Conversation Import Multer Instance Missing File Size Limits Jun 25, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-66451 is "LibreChat's Improper Input Validation in Prompt Creation API Enables Unauthorized Permission Changes", rated Medium. It affects Danny-avila/librechat (Danny-avila); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 0.33% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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