// For flags

CVE-2016-5696

kernel: challenge ACK counter information disclosure.

Severity Score

4.8
*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

5
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

net/ipv4/tcp_input.c en el kernel de Linux en versiones anteriores a 4.7 no determina adecuadamente la tasa de segmentos de desafío ACK, lo que facilita a atacantes remotos secuestrar sesiones TCP a través de un ataque ciego en ventana.

It was found that the RFC 5961 challenge ACK rate limiting as implemented in the Linux kernel's networking subsystem allowed an off-path attacker to leak certain information about a given connection by creating congestion on the global challenge ACK rate limit counter and then measuring the changes by probing packets. An off-path attacker could use this flaw to either terminate TCP connection and/or inject payload into non-secured TCP connection between two endpoints on the network.

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix: A flaw was found in the Linux kernel's keyring handling code, where in key_reject_and_link() an uninitialised variable would eventually lead to arbitrary free address which could allow attacker to use a use-after-free style attack. A flaw was found in the way certain interfaces of the Linux kernel's Infiniband subsystem used write() as bi-directional ioctl() replacement, which could lead to insufficient memory security checks when being invoked using the splice() system call. A local unprivileged user on a system with either Infiniband hardware present or RDMA Userspace Connection Manager Access module explicitly loaded, could use this flaw to escalate their privileges on the system.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low
Attack Vector
Network
Attack Complexity
Medium
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2016-06-16 CVE Reserved
  • 2016-08-06 CVE Published
  • 2020-10-18 First Exploit
  • 2024-08-06 CVE Updated
  • 2025-03-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-203: Observable Discrepancy
CAPEC
References (37)
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Google
Search vendor "Google"
Android
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<= 7.0
Search vendor "Google" for product "Android" and version " <= 7.0"
-
Affected
Oracle
Search vendor "Oracle"
Vm Server
Search vendor "Oracle" for product "Vm Server"
3.3
Search vendor "Oracle" for product "Vm Server" and version "3.3"
-
Affected
Oracle
Search vendor "Oracle"
Vm Server
Search vendor "Oracle" for product "Vm Server"
3.4
Search vendor "Oracle" for product "Vm Server" and version "3.4"
-
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
<= 4.6.6
Search vendor "Linux" for product "Linux Kernel" and version " <= 4.6.6"
-
Affected