High severity · published Sep 29, 2026
CVE-2026-54873
QUIC STREAM Fragment Metadata DoS
7.5
CVSS
0.7%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 53% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OP
OpenSSL · OpenSSL
4.0.0 before 4.0.3; 3.6.0 before 3.6.5; 3.5.0 before 3.5.9; 3.4.0 before 3.4.8 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54873
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-54873
vendor-advisory
https://openssl-library.org/news/secadv/20260929.txt
patch
https://github.com/openssl/openssl/commit/1f643b8bc735487b500a1f68a7fb3a22d5e38e23
patch
https://github.com/openssl/openssl/commit/7127fb10888b49711c63128a09e524c0d2d5d0b2
patch
https://github.com/openssl/openssl/commit/279e7ee1392af98785746788168749491c74bd53
patch
https://github.com/openssl/openssl/commit/3ea6213e050e938ecbbf8c4eff32bec2736780eb
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