CVE-2026-93840 (CVSS 3.7)

Description

vLLM before 0.29.0 validates allowed_token_ids against tokenizer length instead of model output logits width in SamplingParams._validate_allowed_token_ids(). Attackers can supply token IDs above the output vocabulary that pass validation, causing LogitBiasState to corrupt GPU logits state and allow concurrent requests to sample tokens outside their allowlists.

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CVSS v3.1 Score

3.7

LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0025

Probability of exploitation

0.15%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-129 CWE-129

References

Other References

https://github.com/vllm-project/vllm https://github.com/vllm-project/vllm/blob/v0.28.0/vllm/sampling_params.py#L881-L903 https://github.com/vllm-project/vllm/blob/v0.28.0/vllm/v1/worker/gpu/sample/logit_bias.py#L179-L191 https://github.com/vllm-project/vllm/commit/5b0e5b69ac1a3884a6479c9537789c95263cc804 https://github.com/vllm-project/vllm/pull/49080 https://www.vulncheck.com/advisories/vllm-before-0.29.0-cross-request-logits-corruption-via-allowed-token-ids

Frequently Asked Questions

What is CVE-2026-93840? +

vLLM before 0.29.0 validates allowed_token_ids against tokenizer length instead of model output logits width in SamplingParams._validate_allowed_token_ids(). Attackers can supply token IDs above the output vocabulary that pass validation, causing LogitBiasState to corrupt GPU logits state and allow concurrent requests to sample tokens outside their allowlists. It has a CVSS v3.1 base score of 3.7 (LOW).

How severe is CVE-2026-93840? +

CVE-2026-93840 has a CVSS v3.1 score of 3.7 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0025, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-93840? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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