QUIC Unvalidated Amplification Credit may be Over Accounted
Summary
| CVE | CVE-2026-35191 |
|---|---|
| State | PUBLISHED |
| Assigner | openssl |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-29 16:17:07 UTC |
| Updated | 2026-09-30 21:17:10 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v3.1 3.7 LOW from ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Problem Types: CWE-440 | CWE-440 CWE-440 Expected Behavior Violation
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 3.7 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 3.7 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/openssl/openssl/commit/2de4c35fb13fc58f43fd8dc1d261700472ce72e5 | [email protected] | github.com | |
| github.com/openssl/openssl/commit/e44292e58b090014232ef75bd400393851b24d1a | [email protected] | github.com | |
| github.com/openssl/openssl/commit/0fe4442d4f8ea3af8a174046dae176e0d4717239 | [email protected] | github.com | |
| openssl-library.org/news/secadv/20260929.txt | [email protected] | openssl-library.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Ali Firas (en)
CNA: Nikolas Gauder (NVIDIA) (en)
CNA: Neil Horman (en)
There are currently no legacy QID mappings associated with this CVE.