Bug 2552477 - CVE-2026-35191 openssl3: openssl: Traffic amplification Denial of Service via QUIC packet over-accounting [epel-all]
Summary: CVE-2026-35191 openssl3: openssl: Traffic amplification Denial of Service via...
Keywords:
Status: NEW
Alias: None
Product: Fedora EPEL
Classification: Fedora
Component: openssl3
Version: epel10
Hardware: Unspecified
OS: Unspecified
low
low
Target Milestone: ---
Assignee: Robert Scheck
QA Contact:
URL:
Whiteboard: {"flaws": ["eeeeb2e8-402e-40f9-a1ec-c...
Depends On:
Blocks: CVE-2026-35191
TreeView+ depends on / blocked
 
Reported: 2026-10-14 17:06 UTC by Srikanth Balasubramanian
Modified: 2026-10-14 17:06 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:


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Description Srikanth Balasubramanian 2026-10-14 17:06:44 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Issue summary: The OpenSSL QUIC server, when configured to not preform address
validation, can be forced to count incoming packets multiple times in its
unvalidated credit computation, leading to a violation of the RFC 9000
unvalidated connection amplification limit of 3 times the amount of data
received.

Impact summary: A remote attacker able to spoof packets to a server using the
OpenSSL QUIC implementation might use the server for an amplification of
a DDoS attack.

CWE: CWE-440: Expected Behavior Violation 

Description: OpenSSL's QUIC stack, when operating as a server, enforces client
address validation (RFC 9000, Section 8), to confirm the peer address is not
used for a traffic amplification attack.  If this feature is disabled on the
server, the QUIC stack limits the amount of server data that can be sent to 3
times the amount of data received from the peer address, until such time as the
TLS handshake is completed.

The OpenSSL QUIC server, when operating in non-validation mode, adds the
length of the whole datagram received to the unvalidated credit limit when
processing each QUIC packet in the datagram. A remote peer may,
after establishing a connection with an initial client hello frame, send a
subsequent datagram containing multiple QUIC packets, leading the server to
account the entire datagram length for each packet in the datagram, resulting
in the server believing that the peer has sent more data than it actually has,
thereby violating the 3x amplification limit mandated by the RFC.

FIPS impact: no
As the QUIC stack lives outside the FIPS module boundary, no FIPS modules
are affected by this CVE.


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