CVE-2026-42772Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC
Updated under an hour ago ()
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It affects OpenSSL. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.3 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-407
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- openssl
- NVD analysis
- Analyzed
- Record last updated
- Sep 30, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
OpenSSL OpenSSL openssl:openssl (from the name) | from 4.0.0 before 4.0.3; from 3.6.0 before 3.6.5; from 3.5.0 before 3.5.9; from 3.4.0 before 3.4.8 | CNA record |
openssl openssl openssl:openssl | from 3.4.0 before 3.4.8; from 3.5.0 before 3.5.9; from 3.6.0 before 3.6.5; from 4.0.0 before 4.0.3 | NVD |
References
- https://openssl-library.org/news/secadv/20260929.txtvendor-advisory
- https://github.com/openssl/openssl/commit/f42ae513bbda513b3c121d54834040ee4a0eae1apatch
- https://github.com/openssl/openssl/commit/32d0ed8afe1b8c3e7ece725b44663da3d7087a09patch
- https://github.com/openssl/openssl/commit/ca8402e273af4de5b3f04fa61a0f0c02ce3ae20epatch
- https://github.com/openssl/openssl/commit/eb2becc0a4baea7f3050a247834d0e5c2ebe1773patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.