# CVE-2016-5696: Information disclosure in n/a > Remote attackers can hijack TCP sessions via blind in-window attacks due to improper challenge ACK rate limiting in the Linux kernel. - **Severity:** Medium 4.8 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 6 Aug 2016 - **Updated:** 6 Aug 2024 - **Also known as:** CVE-2016-5389, DEBIAN-CVE-2016-5696, GHSA-26qg-wc7f-8867, RHSA-2016:1631, RHSA-2016:1632, RHSA-2016:1633, RHSA-2016:1664, RHSA-2016:1815, RHSA-2016:1939, UBUNTU-CVE-2016-5696 ## What is CVE-2016-5696? CVE-2016-5696 is a medium-severity vulnerability in Google Android, published on 6 Aug 2016. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description net/ipv4/tcp_input.c in the Linux kernel before 4.7 does not properly determine the rate of challenge ACK segments, which makes it easier for remote attackers to hijack TCP sessions via a blind in-window attack. Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) ## Which versions are affected by CVE-2016-5696? It affects 3 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `kernel` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-abi-whitelists` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug-debuginfo` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug-devel` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo-common-i686` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo-common-x86_64` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-devel` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-doc` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-firmware` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-headers` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `perf` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `perf-debuginfo` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `python-perf` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `python-perf-debuginfo` | Red Hat:enterprise_linux:6::client | All versions | 0:2.6.32-642.4.2.el6 | | `kernel` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-abi-whitelists` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug-debuginfo` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug-devel` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo-common-i686` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo-common-x86_64` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-devel` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-doc` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-firmware` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-headers` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `perf` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `perf-debuginfo` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `python-perf` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `python-perf-debuginfo` | Red Hat:enterprise_linux:6::computenode | All versions | 0:2.6.32-642.4.2.el6 | | `kernel` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-abi-whitelists` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-bootwrapper` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug-debuginfo` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debug-devel` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | | `kernel-debuginfo-common-i686` | Red Hat:enterprise_linux:6::server | All versions | 0:2.6.32-642.4.2.el6 | Products: Google Android, Linux kernel, Oracle Vm Server. ## How do I fix CVE-2016-5696? Upgrade to a fixed version. ## Is CVE-2016-5696 being exploited? There is no known exploitation of CVE-2016-5696 in the wild and no public exploit code. Public exploit code: - Proof of Concept code for CVE-2016-5696 (github_poc): https://github.com/violentshell/rover - Proof-of-concept exploit code for CVE-2016-5696 (github_poc): https://github.com/jduck/challack - A PoC demonstrating techniques exploiting CVE-2016-5696 Off-Path TCP Exploits: Global Rate Limit Considered Dangerous (github_poc): https://github.com/Gnoxter/mountain_goat - Daemon to randomize tcp_challenge_ack_limit to prevent side channel attacks CVE-2016-5696 (github_poc): https://github.com/bplinux/chackd - global rate-limiting in Linux (CVE-2016-5696) scanner (github_poc): https://github.com/unkaktus/grill ## Other vulnerabilities in Google Android - [CVE-2026-58704](https://insights.sbomify.com/CVE-2026-58704/): Google Pixel Improper Authorization (high 8.8, exploited in the wild) - [CVE-2025-48543](https://insights.sbomify.com/CVE-2025-48543/): Android Runtime Use-After-Free (high 8.8, exploited in the wild) - [CVE-2023-35674](https://insights.sbomify.com/CVE-2023-35674/): Android Framework Privilege Escalation (high 8.8, exploited in the wild) - [CVE-2025-48595](https://insights.sbomify.com/CVE-2025-48595/): Android Framework Integer Overflow (high 8.4, exploited in the wild) - [CVE-2024-32896](https://insights.sbomify.com/CVE-2024-32896/): Android Pixel Privilege Escalation (high 8.1, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2016-5696 and fix it if it is affected. What it is: CVE-2016-5696 is a medium-severity vulnerability in Google Android, published on 6 Aug 2016. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2016-5696 in the wild and no public exploit code. Affected product: Google Android. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2016-5696/ (Markdown: https://insights.sbomify.com/CVE-2016-5696/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2016-5696 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-5696 - OSV: https://osv.dev/vulnerability/CVE-2016-5696 --- From sbomify Insights: https://insights.sbomify.com/CVE-2016-5696/ Summaries are generated and may contain mistakes; the official description above is the record.