USN-8861-1: OpenSSL vulnerabilities
Ubuntu patches two OpenSSL QUIC denial-of-service flaws that can exhaust CPU or memory.
Ubuntu Security Notice USN-8861-1 covers two OpenSSL vulnerabilities in QUIC handling. CVE-2026-42772 is an inefficient stream-reassembly algorithm that a remote attacker could use to consume excessive CPU. CVE-2026-54873 does not properly limit memory allocated for QUIC packet buffers, which could exhaust memory. Both issues can cause denial of service, and the notice does not report active exploitation.
- CVE-2026-42772 can drive excessive CPU use during QUIC stream reassembly.
- CVE-2026-54873 can exhaust memory through unbounded QUIC packet buffers.
- Both are remote denial-of-service issues; active exploitation is not reported.
Vulnerabilities mentionedAll →
- CVE-2026-548737.5—Issue summary: QUIC process may keep memory for QUIC packet buffer for much longer period than necessarypublished · openssl openssl+1 related
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
CVE-2026-54873+1 related CVE | Issue summary: QUIC process may keep memory for QUIC packet buffer for much longer period than necessary Issue summary: QUIC process may keep memory for QUIC packet buffer for much longer period than necessary. Impact summary: Remote peer can exploit this vulnerability by sending maliciously crafted packets, making the local QUIC stack to keep the memory for packet buffers allocated. The time for which the memory remains allocated is entirely under the control of the potentially malicious remote peer. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: To save copy operation from the packet buffer to the stream reassemble buffer the QUIC stack leaves the stream data on the packet buffer waiting to be copied to a buffer provided by the local receiving application. The QUIC stack releases a reference to the packet buffer only after the data are copied to the application buffer. This design is more efficient for legitimate data transfers but enables an attacker to allocate a lot more memory than actually required by the data kept in the receiving stream buffer. To mitigate the vulnerability, the QUIC stack now calculates and monitors memory overhead for every stream. The memory overhead for a single stream frame is calculated as a difference between the size of the whole packet that carries the stream frame and the size of the stream frame itself. The memory overhead for a single stream frame is added to the total (cumulative) memory overhead QUIC stack keeps for each stream. Once the cumulative memory overhead exceeds 64kB, the QUIC stack moves the stream frame data from the packet buffer to the stream buffer, starting with the next packet received. FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary. |
It was discovered that OpenSSL had an inefficient algorithm in its QUIC stream reassembly implementation. A remote attacker could possibly use this issue to cause OpenSSL to use excessive CPU resources, leading to a denial of service. (CVE-2026-42772) It was discovered that OpenSSL did not properly limit memory allocated for QUIC packet buffers. A remote attacker could possibly use this issue to cause OpenSSL to use excessive memory resources, leading to a denial of service. (CVE-2026-54873)
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