Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC
Summary
| CVE | CVE-2026-42772 |
|---|---|
| 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 QUIC stream reassembly algorithm performance deteriorates progressively as packets are arriving out of order. The worst case has a quadratic complexity proportional to the number of stream frames kept in the buffer for the received stream data. Impact summary: A remote QUIC peer that completes the handshake can create a connection-scoped CPU pressure and potentially a Denial of Service using compliant STREAM frames inside the advertised receive window, with low attacker bandwidth. CWE: CWE-407: Inefficient Algorithmic Complexity Description: OpenSSL manages received QUIC stream fragments using a doubly-linked list. While it optimizes for append operations (at the end of the list), it falls back to a head-to-tail linear search for any fragment that does not immediately follow the current `tail`. By manipulating the sequence of offsets, an attacker can force the server to perform O(n^2) operations, consuming excessive CPU time for the QUIC process. FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary. |
Risk And Classification
Primary CVSS: v3.1 5.3 MEDIUM from ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS: 0.003300000 probability, percentile 0.236890000 (date 2026-10-01)
Problem Types: CWE-407 | CWE-407 CWE-407 Inefficient Algorithmic Complexity
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 5.3 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 5.3 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
LowCVSS:3.1/AV:N/AC:L/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/32d0ed8afe1b8c3e7ece725b44663da3d7087a09 | [email protected] | github.com | |
| github.com/openssl/openssl/commit/eb2becc0a4baea7f3050a247834d0e5c2ebe1773 | [email protected] | github.com | |
| openssl-library.org/news/secadv/20260929.txt | [email protected] | openssl-library.org | |
| github.com/openssl/openssl/commit/ca8402e273af4de5b3f04fa61a0f0c02ce3ae20e | [email protected] | github.com | |
| github.com/openssl/openssl/commit/f42ae513bbda513b3c121d54834040ee4a0eae1a | [email protected] | github.com | |
| 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: Saku0512 (en)
CNA: Opal Wright (Trail of Bits) (en)
CNA: Alexandr Nedvedicky (en)
There are currently no legacy QID mappings associated with this CVE.