CVE-2026-23247 | Linux Kernel up to 6.18.16/6.19.6/7.0-rc2 tcp siphash downgrade (EUVD-2026-12810)

VDB-351522 · CVE-2026-23247 · EUVD-2026-12810 LINUX KERNEL UP TO 6.18.16/6.19.6/7.0-RC2 TCP SIPHASH DOWNGRADE HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 3.6 $0-$5k 0.94 Summaryinfo A vulnerability labeled as problematic has been found in Linux Kernel up to 6.18.16/6.19.6/7.0-rc2. The affected element is the function siphash of the component tcp. The manipulation results in downgrade. This vulnerability is reported as CVE-2026-23247. The attack can be launched remotely. No exploit exists. The affected component should be upgraded. Detailsinfo A vulnerability classified as problematic has been found in Linux Kernel up to 6.18.16/6.19.6/7.0-rc2. Affected is the function siphash of the component tcp. The manipulation with an unknown input leads to a downgrade vulnerability. CWE is classifying the issue as CWE-757. A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. This is going to have an impact on confidentiality. CVE summarizes: In the Linux kernel, the following vulnerability has been resolved: tcp: secure_seq: add back ports to TS offset This reverts 28ee1b746f49 ("secure_seq: downgrade to per-host timestamp offsets") tcp_tw_recycle went away in 2017. Zhouyan Deng reported off-path TCP source port leakage via SYN cookie side-channel that can be fixed in multiple ways. One of them is to bring back TCP ports in TS offset randomization. As a bonus, we perform a single siphash() computation to provide both an ISN and a TS offset. The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-23247 since 01/13/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 03/18/2026). This vulnerability is assigned to T1562.010 by the MITRE ATT&CK project. Upgrading to version 6.18.17, 6.19.7 or 7.0-rc3 eliminates this vulnerability. Applying the patch eae2f14ab2efccdb7480fae7d42c4b0116ef8805/46e5b0d7cf55821527adea471ffe52a5afbd9caf/165573e41f2f66ef98940cf65f838b2cb575d9d1 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version. The vulnerability is also documented in the databases at EUVD (EUVD-2026-12810) and CERT Bund (WID-SEC-2026-0774). Affected Open Source Linux Kernel Productinfo Type Operating System Vendor Linux Name Kernel Version 6.18.0 6.18.1 6.18.2 6.18.3 6.18.4 6.18.5 6.18.6 6.18.7 6.18.8 6.18.9 6.18.10 6.18.11 6.18.12 6.18.13 6.18.14 6.18.15 6.18.16 6.19.0 6.19.1 6.19.2 6.19.3 6.19.4 6.19.5 6.19.6 7.0-rc1 7.0-rc2 License open-source Website Vendor: https://www.kernel.org/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 3.7 VulDB Meta Temp Score: 3.6 VulDB Base Score: 3.7 VulDB Temp Score: 3.6 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Downgrade CWE: CWE-757 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: Kernel 6.18.17/6.19.7/7.0-rc3 Patch: eae2f14ab2efccdb7480fae7d42c4b0116ef8805/46e5b0d7cf55821527adea471ffe52a5afbd9caf/165573e41f2f66ef98940cf65f838b2cb575d9d1 Timelineinfo 01/13/2026 CVE reserved 03/18/2026 +64 days Advisory disclosed 03/18/2026 +0 days VulDB entry created 03/18/2026 +0 days VulDB entry last update Sourcesinfo Vendor: kernel.org Advisory: git.kernel.org Status: Confirmed CVE: CVE-2026-23247 (🔒) GCVE (CVE): GCVE-0-2026-23247 GCVE (VulDB): GCVE-100-351522 EUVD: 🔒 CERT Bund: WID-SEC-2026-0774 - Linux Kernel: Mehrere Schwachstellen Entryinfo Created: 03/18/2026 11:59 Updated: 03/18/2026 16:08 Changes: 03/18/2026 11:59 (59), 03/18/2026 12:24 (1), 03/18/2026 16:08 (7) Complete: 🔍 Cache ID: 99:EBA:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸