vulnerability
Red Hat: CVE-2025-66199: openssl: OpenSSL: Denial of Service due to excessive memory allocation in TLS 1.3 certificate compression (Multiple Advisories)
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 7 | (AV:N/AC:M/Au:N/C:N/I:N/A:C) | Jan 27, 2026 | Jan 29, 2026 | Jan 29, 2026 |
Severity
7
CVSS
(AV:N/AC:M/Au:N/C:N/I:N/A:C)
Published
Jan 27, 2026
Added
Jan 29, 2026
Modified
Jan 29, 2026
Description
A flaw was found in OpenSSL. A remote attacker can exploit this vulnerability by sending a specially crafted CompressedCertificate message during the TLS 1.3 handshake. This can cause excessive per-connection memory allocations, leading to resource exhaustion and a Denial of Service (DoS) for affected clients and servers. This issue occurs when TLS 1.3 certificate compression is enabled and negotiated.
Solutions
redhat-upgrade-opensslredhat-upgrade-openssl-debuginforedhat-upgrade-openssl-debugsourceredhat-upgrade-openssl-develredhat-upgrade-openssl-libsredhat-upgrade-openssl-libs-debuginforedhat-upgrade-openssl-perl
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