PYSEC-2026-3479

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/litellm/PYSEC-2026-3479.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-3479
Aliases
Published
2026-07-23T11:41:48.668599Z
Modified
2026-07-23T15:00:13.909880217Z
Severity
  • 8.8 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
Details

Impact

LiteLLM's MCP Streamable HTTP endpoint could allow an unauthenticated attacker to establish an authenticated MCP session using an arbitrary Bearer token.

The MCP auth handler supported OAuth2 passthrough for upstream MCP servers, but the fallback path could replace failed LiteLLM key validation with an empty UserAPIKeyAuth() object. This allowed requests with a fabricated Authorization header to reach MCP tooling without a valid LiteLLM key.

An attacker could use this to list and call configured MCP tools and access connected services exposed through MCP.

Patches

The issue is fixed in 1.84.0.

We recommend upgrading to 1.84.0 or later.

Workarounds

If upgrading is not immediately possible, disable MCP routes or block access to /mcp/ and related MCP endpoints at your reverse proxy or API gateway.

References

References

Affected packages

PyPI / litellm

Package

Name
litellm
View open source insights on deps.dev
Purl
pkg:pypi/litellm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.84.0

Affected versions

0.*
0.1.0
0.1.1
0.1.2
0.1.3
0.1.31
0.1.32
0.1.34
0.1.201
0.1.202
0.1.203
0.1.204
0.1.205
0.1.206
0.1.207
0.1.208
0.1.209
0.1.210
0.1.211
0.1.212
0.1.213
0.1.214
0.1.215
0.1.216
0.1.217
0.1.218
0.1.219
0.1.220
0.1.221
0.1.222
0.1.223
0.1.224
0.1.225
0.1.226
0.1.227
0.1.228
0.1.229
0.1.230
0.1.231
0.1.232
0.1.233
0.1.234
0.1.235
0.1.236
0.1.237
0.1.238
0.1.330
0.1.331
0.1.341
0.1.343
0.1.345
0.1.347
0.1.348
0.1.349
0.1.351
0.1.352
0.1.353
0.1.354
0.1.356
0.1.360
0.1.361
0.1.362
0.1.363
0.1.364
0.1.365
0.1.366
0.1.367
0.1.368
0.1.369
0.1.370
0.1.371
0.1.372
0.1.373
0.1.375
0.1.376
0.1.379
0.1.380
0.1.381
0.1.383
0.1.384
0.1.385
0.1.386
0.1.387
0.1.388
0.1.389
0.1.392
0.1.393
0.1.394
0.1.398
0.1.399
0.1.400
0.1.401
0.1.402
0.1.403
0.1.404
0.1.405
0.1.410
0.1.411
0.1.412
0.1.415
0.1.419
0.1.420
0.1.421
0.1.422
0.1.424
0.1.425
0.1.426
0.1.429
0.1.433
0.1.434
0.1.435
0.1.436
0.1.437
0.1.438
0.1.439
0.1.440
0.1.441
0.1.442
0.1.443
0.1.444
0.1.445
0.1.446
0.1.447
0.1.448
0.1.449
0.1.450
0.1.451
0.1.452
0.1.456
0.1.457
0.1.459
0.1.460
0.1.461
0.1.464
0.1.465
0.1.475
0.1.477
0.1.479
0.1.480
0.1.481
0.1.482
0.1.486
0.1.487
0.1.488
0.1.490
0.1.491
0.1.492
0.1.493
0.1.494
0.1.495
0.1.497
0.1.500
0.1.501
0.1.504
0.1.507
0.1.508
0.1.509
0.1.510
0.1.511
0.1.512
0.1.516
0.1.517
0.1.518
0.1.520
0.1.525
0.1.530
0.1.531
0.1.533
0.1.535
0.1.536
0.1.537
0.1.538
0.1.544
0.1.546
0.1.547
0.1.548
0.1.549
0.1.550
0.1.551
0.1.552
0.1.553
0.1.554
0.1.555
0.1.556
0.1.557
0.1.558
0.1.559
0.1.560
0.1.561
0.1.562
0.1.563
0.1.567
0.1.568
0.1.569
0.1.570
0.1.574
0.1.578
0.1.580
0.1.582
0.1.583
0.1.585
0.1.586
0.1.587
0.1.590
0.1.591
0.1.593
0.1.595
0.1.596
0.1.597
0.1.598
0.1.600
0.1.601
0.1.604
0.1.605
0.1.607
0.1.609
0.1.610
0.1.615
0.1.618
0.1.619
0.1.620
0.1.621
0.1.623
0.1.624
0.1.625
0.1.626
0.1.629
0.1.630
0.1.631
0.1.632
0.1.634
0.1.635
0.1.636
0.1.638
0.1.639
0.1.641
0.1.642
0.1.643
0.1.644
0.1.645
0.1.646
0.1.647
0.1.648
0.1.649
0.1.650
0.1.651
0.1.652
0.1.674
0.1.680
0.1.681
0.1.683
0.1.685
0.1.686
0.1.687
0.1.689
0.1.690
0.1.692
0.1.693
0.1.696
0.1.697
0.1.698
0.1.700.dev0
0.1.700.dev1
0.1.700.dev2
0.1.700.dev3
0.1.700.dev4
0.1.700.dev5
0.1.700
0.1.702
0.1.704
0.1.706
0.1.714.dev1
0.1.714
0.1.715
0.1.716
0.1.719
0.1.720
0.1.721
0.1.723
0.1.724
0.1.729
0.1.736
0.1.738
0.1.743
0.1.745
0.1.746
0.1.747
0.1.748
0.1.749
0.1.750
0.1.751
0.1.758
0.1.765
0.1.769
0.1.772
0.1.774
0.1.780
0.1.781
0.1.784
0.1.786
0.1.788
0.1.789
0.1.793
0.1.794
0.1.805
0.1.806
0.1.807
0.1.813
0.1.814
0.1.815
0.1.816
0.1.817
0.1.818
0.1.819
0.1.820
0.1.821
0.1.824
0.1.2291
0.1.7701
0.1.7713
0.2.5
0.2.6
0.3.0
0.3.1
0.4.0
0.4.4
0.5.2
0.5.3
0.5.4
0.5.6
0.6.0
0.6.1
0.6.2
0.6.6
0.7.1.dev1
0.7.1.dev2
0.7.1.dev3
0.7.1
0.7.3
0.7.4
0.7.5
0.7.9
0.7.10
0.8.0
0.8.1
0.8.2
0.8.3
0.8.4
0.8.5
0.8.6
0.9.0
0.9.1
0.9.2.dev1
0.9.2
0.10.0
0.10.1
0.11.1
0.12.4.dev1
0.12.4.dev2
0.12.4
0.12.5.dev1
0.12.5
0.12.7.dev1
0.12.7
0.12.8
0.12.9
0.12.10
0.12.11
0.12.12
0.13.0
0.13.1.dev1
0.13.1.dev2
0.13.1.dev3
0.13.1
0.13.2.dev1
0.13.2
0.13.3.dev1
0.13.3.dev2
0.13.6.dev1
0.13.6.dev2
0.13.6.dev3
0.13.7.dev1
0.14.0.dev1
0.14.0
0.14.1
1.*
1.0.0.dev1
1.0.0
1.0.3.dev1
1.0.3
1.1.0
1.1.1
1.1.2
1.1.3
1.2.0
1.3.1
1.3.3.dev1
1.3.3.dev2
1.3.3.dev3
1.3.3
1.4.0
1.6.0
1.7.1
1.7.2
1.7.3
1.7.4
1.7.5
1.7.6
1.7.7
1.7.8
1.7.9
1.7.11
1.7.12
1.8.1
1.9.dev0
1.9.0
1.9.1
1.9.2
1.9.3
1.9.4
1.9.5
1.10.dev11
1.10.0
1.10.1
1.10.2
1.10.3
1.10.4
1.10.6
1.10.8
1.10.9
1.10.10
1.10.11
1.11.0
1.11.1
1.12.0
1.12.1
1.12.2
1.12.3
1.12.5.dev1
1.12.5
1.12.6.dev1
1.12.6.dev2
1.12.6.dev3
1.12.6.dev4
1.12.6.dev5
1.13.2
1.14.0.dev1
1.14.0
1.14.1
1.14.2
1.14.3
1.14.4
1.14.5.dev1
1.14.5
1.14.6
1.14.7
1.14.8
1.14.9
1.14.10
1.15.0
1.15.1
1.15.2
1.15.3
1.15.6
1.15.7
1.15.8
1.15.10
1.16.0
1.16.1
1.16.2
1.16.3
1.16.4
1.16.5
1.16.6
1.16.7
1.16.8
1.16.9
1.16.11
1.16.12
1.16.18
1.16.19
1.16.20
1.16.21
1.17.0
1.17.2
1.17.3
1.17.4
1.17.5
1.17.9
1.18.0
1.18.1
1.18.2
1.18.6
1.18.7
1.18.8
1.18.13.dev1
1.18.13.dev4
1.18.13.dev5
1.18.13
1.18.14.dev8
1.19.4
1.20.0
1.20.5
1.20.6
1.20.7
1.20.8
1.20.9
1.21.4.dev1
1.21.6
1.21.7
1.22.3
1.22.5
1.23.0
1.23.1
1.23.2
1.23.3
1.23.5
1.23.15
1.23.16
1.24.3
1.24.5
1.25.0
1.25.1
1.25.2
1.26.0
1.26.1
1.26.3
1.26.8
1.26.13
1.27.1.dev9
1.27.1.dev11
1.27.1.dev30
1.27.1.dev31
1.27.1.dev40
1.27.1.dev50
1.27.1.dev60
1.27.4
1.27.6
1.27.8
1.28.0
1.28.1
1.28.4
1.28.10
1.28.11
1.28.13
1.29.1
1.29.3
1.29.4.dev1
1.29.7.dev3
1.30.0
1.30.1.dev5
1.30.1.dev6
1.30.1
1.30.3
1.30.7
1.31.2.dev10
1.31.2
1.31.3
1.31.6
1.31.8
1.31.13.dev1
1.31.13.dev2
1.31.13.dev3
1.31.13.dev10
1.31.14.dev2
1.31.14.dev3
1.31.14.dev4
1.31.14.dev5
1.31.14.dev6
1.31.14.dev8
1.31.14.dev9
1.31.14
1.31.15.dev2
1.31.17
1.32.1
1.32.4
1.32.5.dev1
1.32.9
1.33.4
1.33.5.dev1
1.33.9
1.34.0
1.34.1
1.34.3
1.34.4
1.34.6
1.34.8
1.34.11
1.34.16
1.34.18
1.34.21
1.34.22
1.34.25
1.34.29
1.34.37
1.34.39
1.34.42
1.35.0.dev1
1.35.0
1.35.1
1.35.2
1.35.3
1.35.5
1.35.7
1.35.8
1.35.12
1.35.17
1.35.18
1.35.20
1.35.21
1.35.22
1.35.23
1.35.26
1.35.28
1.35.31
1.35.32
1.35.35
1.35.36
1.35.38
1.36.0
1.36.1
1.36.2
1.36.4
1.37.0
1.37.2
1.37.3
1.37.7
1.37.9
1.37.12
1.37.14
1.37.16
1.37.19
1.37.20
1.38.0
1.38.1
1.38.3
1.38.4
1.38.5
1.38.7
1.38.8
1.38.10
1.38.11
1.38.12
1.39.2
1.39.3
1.39.4
1.39.5.dev1
1.39.5
1.39.6
1.40.0.dev1
1.40.0
1.40.1.dev1
1.40.1
1.40.2
1.40.3
1.40.4
1.40.5
1.40.6
1.40.7
1.40.8
1.40.9
1.40.10
1.40.11
1.40.12
1.40.13
1.40.14
1.40.15
1.40.16
1.40.17
1.40.19
1.40.20
1.40.21
1.40.22
1.40.24
1.40.25
1.40.26
1.40.27
1.40.28
1.40.29
1.40.31
1.41.0
1.41.1
1.41.2
1.41.3
1.41.4
1.41.5
1.41.6
1.41.7
1.41.8
1.41.11
1.41.12
1.41.13
1.41.14
1.41.15.dev2
1.41.15
1.41.17
1.41.18
1.41.19
1.41.20
1.41.21
1.41.22
1.41.23
1.41.24
1.41.25
1.41.26
1.41.27
1.41.28
1.42.0
1.42.1
1.42.2
1.42.3
1.42.4
1.42.5
1.42.6
1.42.7
1.42.8
1.42.9
1.42.10
1.42.11
1.42.12
1.43.0
1.43.1
1.43.2
1.43.3
1.43.4
1.43.5
1.43.6
1.43.7
1.43.9
1.43.10
1.43.12
1.43.13
1.43.15
1.43.16
1.43.17
1.43.18
1.43.19
1.44.1
1.44.2
1.44.3
1.44.4
1.44.5
1.44.6
1.44.7
1.44.8
1.44.9
1.44.10
1.44.11
1.44.12
1.44.13
1.44.14
1.44.15
1.44.16
1.44.17
1.44.18
1.44.19
1.44.21
1.44.22
1.44.23
1.44.24
1.44.25
1.44.26
1.44.27
1.44.28
1.45.0
1.46.0
1.46.1
1.46.2
1.46.4
1.46.5
1.46.6
1.46.7
1.46.8
1.47.0
1.47.1
1.47.2
1.48.0
1.48.1
1.48.2
1.48.3
1.48.4
1.48.5
1.48.6
1.48.7
1.48.8
1.48.9
1.48.10
1.48.11
1.48.12
1.48.14
1.48.15
1.48.16
1.48.17
1.48.18
1.48.19
1.49.0
1.49.1
1.49.2
1.49.3
1.49.4
1.49.5
1.49.6
1.49.7
1.50.0
1.50.1
1.50.2
1.50.4
1.51.0
1.51.1
1.51.2
1.51.3
1.52.0
1.52.1
1.52.2
1.52.3
1.52.4
1.52.5
1.52.6
1.52.8
1.52.9
1.52.10
1.52.11
1.52.12
1.52.14
1.52.15
1.52.16
1.53.1.dev1
1.53.1
1.53.2
1.53.3
1.53.4
1.53.5
1.53.6
1.53.7
1.53.8
1.53.9
1.54.0
1.54.1
1.55.0
1.55.1
1.55.2
1.55.3
1.55.4
1.55.6
1.55.7
1.55.8
1.55.9
1.55.10
1.55.11
1.55.12
1.56.2
1.56.3
1.56.4
1.56.5
1.56.6
1.56.8.dev4
1.56.8.dev5
1.56.8.dev6
1.56.8.dev7
1.56.8
1.56.9
1.56.10
1.57.0
1.57.1
1.57.2
1.57.3
1.57.4
1.57.5
1.57.7.dev1
1.57.7
1.57.8
1.57.10
1.57.11
1.58.0
1.58.1
1.58.2
1.58.4
1.59.0
1.59.1.dev1
1.59.1
1.59.2
1.59.3
1.59.5
1.59.6
1.59.7
1.59.8
1.59.9
1.59.10.dev1
1.59.10
1.59.12
1.60.0
1.60.2
1.60.4
1.60.5
1.60.6
1.60.7
1.60.8
1.60.9
1.61.0.dev1
1.61.0
1.61.1
1.61.2
1.61.3
1.61.4
1.61.5
1.61.6
1.61.7
1.61.8
1.61.9
1.61.11
1.61.13
1.61.15
1.61.16
1.61.17
1.61.19
1.61.20
1.62.1
1.62.4
1.63.0.dev12
1.63.0
1.63.2
1.63.3
1.63.4.dev1
1.63.5
1.63.6
1.63.7
1.63.8
1.63.11.dev1
1.63.11
1.63.12
1.63.14
1.64.1
1.65.0
1.65.0.post1
1.65.1
1.65.3
1.65.4
1.65.4.post1
1.65.5
1.65.6
1.65.7
1.65.8
1.66.0
1.66.1
1.66.2
1.66.3
1.67.0
1.67.0.post1
1.67.1
1.67.2
1.67.4.dev1
1.67.4
1.67.4.post1
1.67.5
1.67.6
1.68.0
1.68.1.dev1
1.68.1
1.68.2
1.69.0
1.69.1
1.69.2
1.69.3
1.70.0
1.70.2
1.70.4
1.71.0
1.71.1
1.71.2
1.71.3
1.72.0
1.72.1
1.72.2
1.72.2.post1
1.72.3
1.72.4
1.72.5.dev1
1.72.5.dev2
1.72.5.dev3
1.72.6
1.72.6.post1
1.72.6.post2
1.72.7.dev1
1.72.7.dev7
1.72.7
1.72.9
1.73.0rc1
1.73.0
1.73.0.post1
1.73.1
1.73.2
1.73.6rc2
1.73.6
1.73.6.post1
1.73.7.dev1
1.73.7.dev2
1.73.7.dev3
1.73.7.dev4
1.73.7
1.74.0
1.74.0.post1
1.74.0.post2
1.74.1
1.74.2
1.74.3rc1
1.74.3rc2
1.74.3rc3
1.74.3
1.74.3.post1
1.74.4.dev1
1.74.4
1.74.6
1.74.7rc1
1.74.7
1.74.7.post1
1.74.7.post2
1.74.8.dev2
1.74.8
1.74.9.dev1
1.74.9.dev2
1.74.9
1.74.9.post1
1.74.9.post2
1.74.12
1.74.14
1.74.15
1.74.15.post1
1.74.15.post2
1.75.0
1.75.2
1.75.3
1.75.4
1.75.5.post1
1.75.5.post2
1.75.6
1.75.7
1.75.8
1.75.9
1.76.0
1.76.1
1.76.2
1.76.3
1.77.0
1.77.1
1.77.2.post1
1.77.3
1.77.4.dev1
1.77.4
1.77.5
1.77.7
1.78.0rc2
1.78.0
1.78.2
1.78.3
1.78.4
1.78.5
1.78.6
1.78.7
1.79.0.dev1
1.79.0.dev2
1.79.0.dev3
1.79.0
1.79.1
1.79.2
1.79.3.dev8
1.79.3
1.80.0
1.80.5
1.80.6
1.80.7
1.80.8
1.80.9
1.80.10
1.80.11
1.80.12
1.80.13
1.80.15
1.80.16
1.80.17
1.81.0
1.81.1
1.81.3
1.81.4
1.81.5
1.81.6
1.81.7
1.81.8
1.81.9.dev1
1.81.9
1.81.10
1.81.11
1.81.12
1.81.13
1.81.14
1.81.15
1.81.16
1.82.0
1.82.1
1.82.2
1.82.3
1.82.4
1.82.5
1.82.6
1.83.0
1.83.1
1.83.2
1.83.3
1.83.4
1.83.5
1.83.6
1.83.7
1.83.8
1.83.9
1.83.10
1.83.11
1.83.12
1.83.13
1.83.14
1.84.0.dev1
1.84.0.dev2
1.84.0rc1

Database specific

source 
"https://github.com/pypa/advisory-database/blob/main/vulns/litellm/PYSEC-2026-3479.yaml"