Eleven OpenSSL CVEs fixed, from QUIC memory bugs to SM2 timing leaks
Serguey Asael Shinder1 min readCanonical published Ubuntu Security Notice USN-8847-1 on 29 September, fixing several OpenSSL vulnerabilities in Ubuntu 26.04 LTS, 24.04 LTS and 22.04 LTS. The notice lists eleven CVEs, from CVE-2026-35189 to CVE-2026-84784.
Most are denial-of-service bugs. OpenSSL mishandled certain certificate revocation list distribution point names, which could exhaust memory. In QUIC it mishandled amplification credit accounting for unvalidated peers, did not correctly enforce connection-level flow control for streams, and could consume excessive memory processing RETIRE_CONNECTION_ID frames. In DTLS, undersized AEAD records in DTLS 1.2 were mishandled before authentication and handshake retransmission could misbehave. A NULL pointer in CMP client revocation response processing could crash the process. A flaw in SSL context switching during a TLS handshake could cause an out-of-bounds read, leading to a crash or information disclosure.
Three issues are timing side channels that could leak sensitive information: scalar multiplication for non-NIST elliptic curves, SM2 scalar multiplication on ARM64 and RISC-V, and SM2 signature generation.
Several of the issues, including the QUIC ones, the SM2 ARM64/RISC-V side channel and the context-switching read, affected only Ubuntu 26.04 LTS. The fix is a standard package update, and the notice says a reboot is needed to apply all changes.
Why it matters
OpenSSL sits under almost every network service on a Linux host, so a batch like this is a routine but not optional update. Teams that enabled QUIC on 26.04 have the most exposure; on older LTS releases the list is shorter, but the side-channel and parsing fixes still apply.