CVE Intelligence
Medium Cross-site scripting exploit reference

CVE-2025-8848 — HTML Injection in Accept-Language Header in danny-avila/librechat

A vulnerability in danny-avila/librechat version 0.7.9 allows for HTML injection via the Accept-Language header. When a logged-in user sends an HTTP GET request with a crafted Accept-Language header, arbitrary HTML can be injected into the <html lang=""> tag of the response. This can lead to potential security risks such as cross-site scripting (XSS) attacks.

Published Oct 22, 2025 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: @huntr_ai

Who exploits it and how urgent it is

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

Detection templates (Nuclei) · 1
How the score was calculated
  • Public exploit/PoC (nuclei)+4
  • EPSS 0.5% (30-day exploitation probability)+6
  • Technical severity (medium)+3

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
0.45%
ahead of 38% of scored CVEs · Oct 14, 2026
Affects
Danny-avila
Danny-avila/librechat and 1 more
CVSS base
5.4
Medium · 4 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
None
none · proof-of-concept · active
Automatable
No
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.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Danny-avila Danny-avila/librechat, Librechat Librechat).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  4. Search available logs for exploit probes matching the vulnerability class (cross-site scripting), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Danny-avila Danny-avila/librechat ≤ latest Vulnerable CVE Program (cve.org) e CISA ADP
Librechat Librechat version 0.7.9 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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
5.4 CVSS 3.1 Medium 2.3 2.7 nvd@nist.gov via NIST National Vulnerability Database
4.8 CVSS 3.0 Medium 1.7 2.7 security@huntr.dev via NIST National Vulnerability Database
4.8 CVSS 3.0 Medium — — GitHub, Inc. via GitHub Security Advisories
4.8 CVSS 3.0 Medium — — @huntr_ai via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 5.4 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-79 · Cross-site Scripting (XSS)

Other CVEs with this weakness →

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Detection templates (Nuclei)

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.45%

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).
  • Monitor CSP violation reports and script payloads in reflected parameters.
web/proxy/WAF logsnetwork IDS/IPSapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · danny-avila/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
  • CVSS changed · 5.4
    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
    Oct 22, 2025 · @huntr_ai

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

Elsewhere on this site

Danny-avila
every CVE for this vendor
Cross-site scripting
same class
CWE-79
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-54040 LibreChat: 2FA Backup Code Regeneration Without OTP Verification Allows 2FA Bypass Jun 25, 2026
  • CVE-2026-54037 LibreChat: Incomplete Fix for CVE-2025-7105 — /api/convos/duplicate Lacks Rate Limiting Applied to /api/convos/fork Jun 25, 2026
  • CVE-2026-54027 LibreChat: Image Upload Route Bypasses Agent Permission Check — Incomplete Fix for File Upload Authorization Jun 25, 2026
  • CVE-2026-54029 LibreChat: IDOR in Message Deletion — Incomplete Fix for CVE-2024-41703 Leaves deleteMessages() Without User Filter Jun 25, 2026
  • CVE-2026-54025 LibreChat: Stored XSS via unescaped image alt text in markdown artifact preview Jun 25, 2026
  • 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 fixed version, patch or mitigation documented.
  • 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-2025-8848 is "HTML Injection in Accept-Language Header in danny-avila/librechat", 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 5.4 describes technical severity. EPSS 0.45% 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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