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CVE-2026-49468

LiteLLM: Authentication Bypass via Host Header Injection

9.5 CriticalPublic exploitFix available

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, a Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. This vulnerability is fixed in 1.84.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

3.03%Up 3.0 points since Jun 12, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.5

LiteLLM: Authentication Bypass via Host Header Injection

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, a Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. This vulnerability is fixed in 1.84.0.

Record
CVE-2026-49468
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-290, CWE-290
Updated
2026-11-02
EUVDEUVD-2026-38361 9.5

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, a Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. This vulnerability is fixed in 1.84.0.

Record
EUVD-2026-38361
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-4xpc-pv4p-pm3w 9.5

LiteLLM: Authentication Bypass via Host Header Injection

Impact

A Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes.

The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched.

Most deployments are not affected. The bypass is blocked by any upstream layer that validates or normalizes Host, such as:

  • a CDN or WAF, such as Cloudflare
  • a reverse proxy with server_name allowlists
  • a host-based load balancer

LiteLLM Cloud customers are not affected.

Patches

Fixed in 1.84.0. Upgrade to 1.84.0 or later. No configuration change is required.

Workarounds

If upgrading is not immediately possible, place the proxy behind an upstream component that validates or normalizes the Host header before forwarding (a CDN/WAF, a reverse proxy with explicit server_name allowlists, or a cloud load balancer with host-based routing rules), or otherwise restrict network access to the proxy listener.

References

Discovery Credit: Le The Thang (KCSC) and Kim Ngoc Chung (One Mount Group)

Record
GHSA-4xpc-pv4p-pm3w
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-290
Updated
2026-11-02
NVD 9.5

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, a Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. This vulnerability is fixed in 1.84.0.

Record
CVE-2026-49468
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-290
Updated
2026-11-02
OSV 9.5

LiteLLM: Authentication Bypass via Host Header Injection

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, a Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. This vulnerability is fixed in 1.84.0.

Record
CVE-2026-49468
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Weakness
CWE-290
Updated
2026-11-02
OSVGHSA-4xpc-pv4p-pm3w 9.5

LiteLLM: Authentication Bypass via Host Header Injection

Impact

A Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes.

The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched.

Most deployments are not affected. The bypass is blocked by any upstream layer that validates or normalizes Host, such as:

  • a CDN or WAF, such as Cloudflare
  • a reverse proxy with server_name allowlists
  • a host-based load balancer

LiteLLM Cloud customers are not affected.

Patches

Fixed in 1.84.0. Upgrade to 1.84.0 or later. No configuration change is required.

Workarounds

If upgrading is not immediately possible, place the proxy behind an upstream component that validates or normalizes the Host header before forwarding (a CDN/WAF, a reverse proxy with explicit server_name allowlists, or a cloud load balancer with host-based routing rules), or otherwise restrict network access to the proxy listener.

References

Discovery Credit: Le The Thang (KCSC) and Kim Ngoc Chung (One Mount Group)

Record
GHSA-4xpc-pv4p-pm3w
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-290
Updated
2026-11-02
OSVPYSEC-2026-388 9.5

LiteLLM: Authentication Bypass via Host Header Injection

Impact

A Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes.

The auth layer derived the effective route from request.url.path in litellm/proxy/auth/auth_utils.py::get_request_route(), which Starlette reconstructs from the Host header. A crafted Host could therefore make the auth gate evaluate a different route from the one FastAPI dispatched.

Most deployments are not affected. The bypass is blocked by any upstream layer that validates or normalizes Host, such as:

  • a CDN or WAF, such as Cloudflare
  • a reverse proxy with server_name allowlists
  • a host-based load balancer

LiteLLM Cloud customers are not affected.

Patches

Fixed in 1.84.0. Upgrade to 1.84.0 or later. No configuration change is required.

Workarounds

If upgrading is not immediately possible, place the proxy behind an upstream component that validates or normalizes the Host header before forwarding (a CDN/WAF, a reverse proxy with explicit server_name allowlists, or a cloud load balancer with host-based routing rules), or otherwise restrict network access to the proxy listener.

References

Discovery Credit: Le The Thang (KCSC) and Kim Ngoc Chung (One Mount Group)

Record
PYSEC-2026-388
CVSS 4.0
9.5 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
litellm
PyPI
 before 1.84.0
1.84.0
litellm
PyPI
 before 1.84.0, plus listed versions
0.1.00.1.10.1.20.1.2010.1.202
Show 45 moreShow less
0.1.2030.1.2040.1.2050.1.2060.1.2070.1.2080.1.2090.1.2100.1.2110.1.2120.1.2130.1.2140.1.2150.1.2160.1.2170.1.2180.1.2190.1.2200.1.2210.1.2220.1.2230.1.2240.1.2250.1.2260.1.2270.1.2280.1.2290.1.22910.1.2300.1.2310.1.2320.1.2330.1.2340.1.2350.1.2360.1.2370.1.2380.1.30.1.310.1.320.1.3300.1.3310.1.340.1.3410.1.343
1.84.0
litellm
PyPI
 before 1.84.0, plus listed versions
0.1.00.1.10.1.20.1.2010.1.202
Show 45 moreShow less
0.1.2030.1.2040.1.2050.1.2060.1.2070.1.2080.1.2090.1.2100.1.2110.1.2120.1.2130.1.2140.1.2150.1.2160.1.2170.1.2180.1.2190.1.2200.1.2210.1.2220.1.2230.1.2240.1.2250.1.2260.1.2270.1.2280.1.2290.1.22910.1.2300.1.2310.1.2320.1.2330.1.2340.1.2350.1.2360.1.2370.1.2380.1.30.1.310.1.320.1.3300.1.3310.1.340.1.3410.1.343
1.84.0

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
NucleiLiteLLM Proxy < 1.84.0 - Host Header Authentication Bypass
PoC in GitHubBiiTts/CVE-2026-49468-LiteLLM-Auth-Bypass2026-07-03
PoC in GitHubkrevetkqqq/CVE-2026-494682026-10-30

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, Nuclei, NVD, OSV, PoC in GitHub

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-49468 is a critical vulnerability (CVSS 9.5) in Berriai Litellm, published June 16, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 3.03%, the 87th percentile. Fixed in litellm 1.84.0.

References

Show 5 moreShow less
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