--- id: CVE-2026-63075 title: |- Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly sends ack-eliciting packets while not acknowledging ACK-only responses, the QUIC stack can retain ACK-only packet metadata for the lifetime of the connection.… summary: |- Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly sends ack-eliciting packets while not acknowledging ACK-only responses, the QUIC stack can retain ACK-only packet metadata for the lifetime of the connection.… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' cwe: - CWE-770 vendor: openssl product: openssl affected: - 'openssl >= 3.4.0, < 3.4.7' - 'openssl >= 3.5.0, < 3.5.8' - 'openssl >= 3.6.0, < 3.6.4' - 'openssl >= 4.0.0, < 4.0.2' patched: - openssl 4.0.2 published: '2026-08-25' updated: '2026-09-11' sourceUpdated: '2026-09-11T21:17:05.403' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63075' references: - url: >- https://github.com/openssl/openssl/commit/7308946576b12e64b8be53bcf0a120354b2b42bc label: openssl-security@openssl.org - url: >- https://github.com/openssl/openssl/commit/7c98d79738549df92868e7dd9be4bbf061eed709 label: openssl-security@openssl.org - url: >- https://github.com/openssl/openssl/commit/bf84721c2548351176e367e6de505792f0118dc6 label: openssl-security@openssl.org - url: >- https://github.com/openssl/openssl/commit/c902e5f16d6a9e130e96d3ca6d8f64d71652e393 label: openssl-security@openssl.org - url: 'https://openssl-library.org/news/secadv/20260825.txt' label: openssl-security@openssl.org - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63075.json - url: 'https://access.redhat.com/security/cve/CVE-2026-63075' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2517570' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-63075' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63075' - url: 'https://access.redhat.com/errata/RHSA-2026:67154' - url: 'https://access.redhat.com/errata/RHSA-2026:67165' - url: 'https://access.redhat.com/errata/RHSA-2026:59641' - url: 'https://access.redhat.com/errata/RHSA-2026:59635' - url: 'https://access.redhat.com/errata/RHSA-2026:67956' - url: 'https://access.redhat.com/errata/RHSA-2026:71603' tags: - nvd - csaf - vex - red-hat epss: 0.00778 epssPercentile: 0.54053 ingestedAt: '2026-09-12T00:03:49.031Z' --- ## Overview Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly sends ack-eliciting packets while not acknowledging ACK-only responses, the QUIC stack can retain ACK-only packet metadata for the lifetime of the connection. Impact summary: A remote peer that can complete a QUIC handshake can cause connection-scoped memory growth which may lead to Denial of Service through memory exhaustion, especially with sustained traffic or many concurrent QUIC connections. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: When the OpenSSL QUIC stack sends an ACK-only packet, there is no requirement by the QUIC protocol that the peer will acknowledge that ACK-only packet (i.e. it is itself not ack-eliciting). However, the OpenSSL implementation stores the metadata about the ACK frames regardless. In and of itself that's ok, but if a malicious peer establishes a connection, and then drives the connection such that ACK-only packets are forced from the OpenSSL implementation peer (i.e., by sending numerous PING frames), and then withholding any subsequent acks for ack-eliciting data, like legitimate data, said malicious peer can force inappropriate memory growth on the OpenSSL peer, potentially leading to a Denial of Service. The fix is to ensure that we account for the transmission of the ACK-only packet in the packet histories high and low watermark without actually storing the ACK-only packet metadata itself. FIPS impact: no The OpenSSL FIPS module is not affected as the QUIC code is outside the FIPS module boundary. ## Affected - `openssl >= 3.4.0, < 3.4.7` - `openssl >= 3.5.0, < 3.5.8` - `openssl >= 3.6.0, < 3.6.4` - `openssl >= 4.0.0, < 4.0.2` ## Remediation Upgrade past the affected range: - `openssl 4.0.2` ## Vendor advisories - **RHSA-2026:67154** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-09-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:67154) - **RHSA-2026:67165** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-09-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:67165) - **RHSA-2026:59641** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59641) - **RHSA-2026:59635** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59635) - **Red Hat VEX** · Low · affected: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat JBoss Core Services, Red Hat JBoss Web Server 6, Red Hat JBoss Web Server 7, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat JBoss Core Services, Red Hat JBoss Web Server 6, … · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63075.json) - **RHSA-2026:67956** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67956) - **RHSA-2026:71603** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:71603)