KV cache poisoning via 16-bit image hashes
Published Jun 4, 2026 · Updated Jun 4, 2026
Weak hash use in LMCache 0.4.0 through 0.4.6 allows local users to poison multimodal KV cache entries with colliding image identifiers. The hex_hash_to_int16 function masks hexadecimal identifiers to 16 bits or keeps only two SHA-256 bytes before embedding the value in token IDs used to derive cache keys. Exploitation requires low-privileged local access, many chosen multimodal identifiers, and matching prompt structure; a collision can return KV data for a different image and corrupt model output.
Summary
What happened
Weak hash use in LMCache 0.4.0 through 0.4.6 allows local users to poison multimodal KV cache entries with colliding image identifiers. The hex_hash_to_int16 function masks hexadecimal identifiers to 16 bits or keeps only two SHA-256 bytes before embedding the value in token IDs used to derive cache keys. Exploitation requires low-privileged local access, many chosen multimodal identifiers, and matching prompt structure; a collision can return KV data for a different image and corrupt model output.
The record
- CVE
- CVE-2026-10813
- Published
- Jun 4, 2026
- Updated
- Jun 4, 2026
- Vendor
- LMCache
- Product
- LMCache
- Classifications
- CWE-327, CWE-328, T1565.001
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 4, 2026CVE publishedPublication date reported by the CVE source.
- Jun 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.4.0
- Affected versionversion=0.4.1
- Affected versionversion=0.4.2
- Affected versionversion=0.4.3
- Affected versionversion=0.4.4
- Affected versionversion=0.4.5
- Affected versionversion=0.4.6
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- 16-bit multimodal hash collision demonstrationproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo