HTML Injection in Accept-Language Header in danny-avila/librechat

published 2025-10-22 12 mo ago modified 2026-10-08 32 d ago also EUVD-2025-35577

cvss: 4.8; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits: 0; none known, plus a Nuclei check

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.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 12 mo ago (2025-10-30)

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

Nuclei template LibreChat <= 0.7.9 - HTML Injection via Accept-Language Header nuclei detection template
huntr.com https://huntr.com/bounties/a05ebc1f-882a-4adc-b178-d3cefa4b730e referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.0	4.8	CVSS:3.0/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected products

danny-avila danny-avila/librechat

Classification

Weakness

CWE-94 Improper Control of Generation of Code
CWE-79 Improper Neutralization of Input During Web Page Generation

References

huntr.com /bounties/a05ebc1f-882a-4adc-b178-d3cefa4b730e
exploit, third-party-advisory

Sources

CVE List CVE-2025-8848
NVD CVE-2025-8848

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary