Vulnerabilities

Vulnerability · CVE-2026-54873

QUIC STREAM Fragment Metadata DoS

Published Sep 29, 2026 · catalog updated Sep 30, 2026 · OpenSSL OpenSSL

Last checked Oct 27, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-54873. EPSS is 0.70%. Act only if a listed version of OpenSSL OpenSSL is installed.

Severity

High7.5

Known exploitation

Not in CISA/VulnCheck KEV

EPSS

0.70%

Remediation

Advisory link

Affected products

vendor OpenSSL OpenSSL

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.