CVE-2025-66199
Fixed in a distro release EPSS <1%CVSS 5.9
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 corruption or information disclosure occurs. This issue only affects builds where TLS 1.3 certificate compression is compiled in (i.e., not OPENSSL_NO_COMP_ALG) and at least one compression algorithm (brotli, zlib, or zstd) is available, and where the compression extension is negotiated. Both clients receiving a server CompressedCertificate and servers in mutual TLS scenarios receiving a client CompressedCertificate are affected. Servers that do not request client certificates are not vulnerable to client-initiated attacks. Users can mitigate this issue by setting SSL_OP_NO_RX_CERTIFICATE_COMPRESSION to disable receiving compressed certificates. The FIPS modules in 3.6, 3.5, 3.4 and 3.3 are not affected by this issue, as the TLS implementation is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5, 3.4 and 3.3 are vulnerable to this issue. OpenSSL 3.0, 1.1.1 and 1.0.2 are not affected by this issue.
Products: OpenSSL
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux 10 | openssl | 1:3.5.1-7.el10_1.alma.1 |
| AlmaLinux 10 | openssl-devel | 1:3.5.1-7.el10_1.alma.1 |
| AlmaLinux 10 | openssl-libs | 1:3.5.1-7.el10_1.alma.1 |
| AlmaLinux 10 | openssl-perl | 1:3.5.1-7.el10_1.alma.1 |
| AlmaLinux 9 | openssl | 1:3.5.1-7.el9_7 |
| AlmaLinux 9 | openssl-devel | 1:3.5.1-7.el9_7 |
| AlmaLinux 9 | openssl-libs | 1:3.5.1-7.el9_7 |
| AlmaLinux 9 | openssl-perl | 1:3.5.1-7.el9_7 |
| Alpine 3.20 | openssl | 3.3.6-r0 |
| Alpine 3.21 | openssl | 3.3.6-r0 |
| Alpine 3.22 | openssl | 3.5.5-r0 |
| Alpine 3.23 | openssl | 3.5.5-r0 |
| Alpine 3.24 | openssl | 3.5.5-r0 |
| Chainguard | libcrypto3-2.34 | 3.6.1-r0 |
| Chainguard | openssl | 3.6.1-r0 |
| Chainguard | openssl-provider-fips-3.4.0 | 0 |
| Chainguard | openssl-provider-fips-3.6.0 | 0 |
| Debian 13 | openssl | 3.5.4-1~deb13u2 |
| Debian 14 | openssl | 3.5.5-1 |
| Red Hat Enterprise Linux 10.1 | openssl | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 10.1 | openssl-debuginfo | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 10.1 | openssl-debugsource | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 10.1 | openssl-devel | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 10.1 | openssl-libs | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 10.1 | openssl-libs-debuginfo | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 10.1 | openssl-perl | 1:3.5.1-7.el10_1 |
| Red Hat Enterprise Linux 9 | openssl | 1:3.5.1-7.el9_7 |
| Red Hat Enterprise Linux 9 | openssl-debuginfo | 1:3.5.1-7.el9_7 |
| Red Hat Enterprise Linux 9 | openssl-debugsource | 1:3.5.1-7.el9_7 |
| Red Hat Enterprise Linux 9 | openssl-devel | 1:3.5.1-7.el9_7 |
| Red Hat Enterprise Linux 9 | openssl-libs | 1:3.5.1-7.el9_7 |
| Red Hat Enterprise Linux 9 | openssl-libs-debuginfo | 1:3.5.1-7.el9_7 |
| Red Hat Enterprise Linux 9 | openssl-perl | 1:3.5.1-7.el9_7 |
| Red Hat hummingbird 1 | openssl | 0:3.5.6-0.1.hum1 |
| Red Hat hummingbird 1 | openssl-config-fips | 0:3.5.6-0.1.hum1 |
| Red Hat hummingbird 1 | openssl-devel | 0:3.5.6-0.1.hum1 |
| Red Hat hummingbird 1 | openssl-devel-engine | 0:3.5.6-0.1.hum1 |
| Red Hat hummingbird 1 | openssl-libs | 0:3.5.6-0.1.hum1 |
| Red Hat hummingbird 1 | openssl-perl | 0:3.5.6-0.1.hum1 |
| Rocky Linux 10 | openssl | 1:3.5.1-7.el10_1 |
| Rocky Linux 9 | openssl | 1:3.5.1-7.el9_7 |
| SUSE Linux Enterprise Server 16.0 | openssl-3 | 3.5.0-160000.5.1 |
| SUSE Linux Enterprise Server for SAP applications 16.0 | openssl-3 | 3.5.0-160000.5.1 |
| SUSE Linux Micro 6.2 | openssl-3 | 3.5.0-160000.5.1 |
| Ubuntu 22.04 LTS | openssl | 3.0.2-0ubuntu1.21 |
| Ubuntu 24.04 LTS | edk2 | no fix |
| Ubuntu 24.04 LTS | openssl | 3.0.13-0ubuntu3.7 |
| Ubuntu 25.10 | edk2 | no fix |
| Ubuntu 25.10 | openssl | 3.5.3-1ubuntu3 |
| Ubuntu 26.04 LTS | edk2 | no fix |
| Ubuntu 26.04 LTS | edk2-hwe | no fix |
| Ubuntu 26.04 LTS | openssl | 3.5.5-1ubuntu1 |
| Ubuntu 26.10 | edk2 | no fix |
| Ubuntu 26.10 | edk2-hwe | no fix |
| Ubuntu Pro 16.04 LTS | nodejs | no fix |
| Ubuntu Pro 18.04 LTS | nodejs | no fix |
| Ubuntu Pro 22.04 LTS | nodejs | no fix |
| Wolfi | openssl | 3.6.1-r0 |
| openSUSE Leap 16.0 | openssl-3 | 3.5.0-160000.5.1 |
| openSUSE Tumbleweed | openssl-3 | 3.5.3-2.1 |