cvedb.io
CVE-2025-66199
MEDIUM · CVSS 5.9
EPSS exploitation probability: 0%
Published 2026-01-27T16:16:15.777 · Last modified 2026-06-17T09:56:27.733

Summary

Issue summary: A TLS 1.3 connection using certificate compression can be forced to allocate a large buffer before decompression without checking against the configured certificate size limit. Impact summary: An attacker can cause per-connection memory allocations of up to approximately 22 MiB and extra CPU work, potentially leading to service degradation or resource exhaustion (Denial of Service). In affected configurations, the peer-supplied uncompressed certificate length from a CompressedCertificate message is used to grow a heap buffer prior to decompression. This length is not bounded by the max_cert_list setting, which otherwise constrains certificate message sizes. An attacker can exploit this to cause large per-connection allocations followed by handshake failure. No memory corru

Affected products

openssl — openssl

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.