Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
AC:H because TCP-AO is non-default and requires explicit configuration; C:L because disclosure is bounded to 1-3 uninitialized padding bytes, not broad memory.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
Lifecycle Timeline
4DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
tcp: initialize standalone TCP-AO response padding
tcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP responses with TCP-AO options. The option length carries the actual MAC length, but the TCP header length includes the option rounded up to a four-byte boundary.
tcp_ao_hash_hdr() writes the MAC only. Thus, when the MAC length is not four-byte aligned, the one to three bytes after the MAC are left uninitialized and may be transmitted. For the normal TCP-AO hashing mode, those bytes also have to be initialized before computing the MAC.
Initialize only the alignment padding in the TCP-AO branches, before hashing the header. Use TCPOPT_NOP, as in the normal TCP-AO output path. This avoids adding work to non-AO TCP responses while preserving a valid authenticated header.
AnalysisAI
Uninitialized kernel memory disclosure via TCP-AO padding bytes affects Linux kernels since v6.7 (commit decde2586b34). When constructing standalone TCP responses - ACKs and RSTs - with TCP Authentication Option (TCP-AO) enabled, one to three alignment padding bytes following a non-four-byte-aligned MAC are left uninitialized and transmitted on the wire, leaking small amounts of kernel memory to on-path observers. No public exploit exists and EPSS is 0.17% (6th percentile), making this low-urgency despite the vendor-assigned CVSS 7.5 score; the C:H rating is likely overstated given the 1-3 byte disclosure boundary.
Technical ContextAI
TCP-AO (TCP Authentication Option, RFC 5925) provides cryptographic authentication for TCP sessions and was introduced in the Linux kernel around v6.7. The functions tcp_v4_send_ack() and tcp_v6_send_response() build standalone TCP responses that embed TCP-AO options. The option header carries the actual MAC length, but the TCP header length field is rounded up to a four-byte boundary. The kernel's tcp_ao_hash_hdr() writes only the MAC bytes themselves, leaving the one to three alignment padding bytes between the MAC and the next boundary uninitialized. These bytes - which may reside in kernel stack or heap memory - are then transmitted to the remote peer, constituting an information-disclosure side-channel. The root cause is an uninitialized-memory use pattern (analogous to CWE-908), not listed as a CWE in the provided data.
RemediationAI
Upgrade to a patched Linux kernel release: v6.12.101, v6.18.42, or v7.1.6 for stable-branch users, or v7.2-rc5 for mainline tracking. Patch commits are available at https://git.kernel.org/stable/c/bbb7db8c74b0b5d17a695136f0f0806ecd0118f6 (6.12 branch), https://git.kernel.org/stable/c/fadaff3f66e124c3a62237f9c881819a8ac90309 (6.18 branch), https://git.kernel.org/stable/c/a859b280441fb02f64ed4037f03d5c0c34a7a595 (7.1 branch), and https://git.kernel.org/stable/c/e1a9d3cc11829c5414a75eb39c704f461936eb24 (mainline). If patching immediately is not feasible, disabling TCP-AO on all sockets eliminates exposure entirely with no functional impact unless TCP-AO authentication is operationally required. TCP-AO configuration is performed via socket options or routing policy; consult the kernel tcp_ao documentation for teardown steps.
Same technique Information Disclosure
View allVendor StatusVendor
SUSE
Severity: Important| Product | Status |
|---|---|
| SUSE Linux Enterprise Desktop 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP7 | Not-Affected |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | Not-Affected |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | Not-Affected |
| SUSE Linux Enterprise High Availability Extension 16.0 | Affected |
| SUSE Linux Enterprise High Availability Extension 16.0 | Affected |
| SUSE Linux Enterprise High Availability Extension 16.1 | Affected |
| SUSE Linux Enterprise High Availability Extension 16.1 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Live Patching 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Live Patching 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Micro 5.3 | Not-Affected |
| SUSE Linux Enterprise Micro 5.3 | Not-Affected |
| SUSE Linux Enterprise Micro 5.3 | Not-Affected |
| SUSE Linux Enterprise Micro 5.3 | Not-Affected |
| SUSE Linux Enterprise Micro 5.4 | Not-Affected |
| SUSE Linux Enterprise Micro 5.4 | Not-Affected |
| SUSE Linux Enterprise Micro 5.4 | Not-Affected |
| SUSE Linux Enterprise Micro 5.4 | Not-Affected |
| SUSE Linux Enterprise Micro 5.5 | Not-Affected |
| SUSE Linux Enterprise Micro 5.5 | Not-Affected |
| SUSE Linux Enterprise Micro 5.5 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server 16.0 | Affected |
| SUSE Linux Enterprise Server 16.0 | Affected |
| SUSE Linux Enterprise Server 16.1 | Affected |
| SUSE Linux Enterprise Server 16.1 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | Not-Affected |
| SUSE Linux Micro 6.0 | Not-Affected |
| SUSE Linux Micro 6.0 | Not-Affected |
| SUSE Linux Micro 6.0 | Not-Affected |
| SUSE Linux Micro 6.1 | Not-Affected |
| SUSE Linux Micro 6.1 | Not-Affected |
| SUSE Linux Micro 6.1 | Not-Affected |
| SUSE Linux Micro 6.2 | Affected |
| SUSE Linux Micro 6.2 | Affected |
| SUSE Linux Micro Extras 6.0 | Not-Affected |
| SUSE Linux Micro Extras 6.0 | Not-Affected |
| SUSE Linux Micro Extras 6.0 | Not-Affected |
| SUSE Linux Micro Extras 6.1 | Not-Affected |
| SUSE Linux Micro Extras 6.1 | Not-Affected |
| SUSE Real Time Module 15 SP7 | Not-Affected |
| openSUSE Leap 16.0 | Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Live Patching 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Live Patching 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Live Patching 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Live Patching 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Live Patching 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Live Patching 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | Not-Affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Not-Affected |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Not-Affected |
| SUSE Manager Proxy 4.3 | Not-Affected |
| SUSE Manager Proxy LTS 4.3 | Not-Affected |
| SUSE Manager Retail Branch Server 4.3 | Not-Affected |
| SUSE Manager Retail Branch Server LTS 4.3 | Not-Affected |
| SUSE Manager Server 4.3 | Not-Affected |
| SUSE Manager Server LTS 4.3 | Not-Affected |
| SUSE CaaS Platform 4.0 | Not-Affected |
| SUSE Enterprise Storage 6 | Not-Affected |
| SUSE Enterprise Storage 7 | Not-Affected |
| SUSE Enterprise Storage 7.1 | Not-Affected |
| SUSE Linux Enterprise Desktop 11 SP4 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP6 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Micro 5.0 | Not-Affected |
| SUSE Linux Enterprise Micro 5.1 | Not-Affected |
| SUSE Linux Enterprise Micro 5.2 | Not-Affected |
| SUSE Linux Enterprise Micro 5.2 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 11 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 11 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Not-Affected |
| SUSE Manager Proxy 4.0 | Not-Affected |
| SUSE Manager Proxy 4.1 | Not-Affected |
| SUSE Manager Proxy 4.2 | Not-Affected |
| SUSE Manager Retail Branch Server 4.0 | Not-Affected |
| SUSE Manager Retail Branch Server 4.1 | Not-Affected |
| SUSE Manager Retail Branch Server 4.2 | Not-Affected |
| SUSE Manager Server 4.0 | Not-Affected |
| SUSE Manager Server 4.1 | Not-Affected |
| SUSE Manager Server 4.2 | Not-Affected |
| SUSE Real Time Module 15 SP4 | Not-Affected |
| SUSE Real Time Module 15 SP5 | Not-Affected |
| openSUSE Leap 15.3 | Not-Affected |
| openSUSE Leap 15.4 | Not-Affected |
| openSUSE Leap 15.4 | Not-Affected |
| openSUSE Leap 15.5 | Not-Affected |
| openSUSE Leap 15.5 | Not-Affected |
| openSUSE Leap 15.6 | Not-Affected |
Share
External POC / Exploit Code
Leaving vuln.today
EUVD-2026-55500
GHSA-5h3v-9fcc-4vc7