GHSA-vvp9-7p8x-rfvv
ADVISORY - githubSummary
Summary
Decompressing invalid LZ4 data can leak data from uninitialized memory, or can leak content from previous decompression operations when reusing an output buffer.
Details
The LZ4 block format defines a "match copy operation" which duplicates previously written data or data from the user-supplied dict. The position of that data is defined by an offset. The data is copied within the output buffer from the offset to the current output position. However, lz4_flex did not properly detect invalid and out-of-bounds offset values properly, causing it to copy uninitialized data from the output buffer.
Only the block based API functions are affected:
lz4_flex::block::{decompress_into, decompress_into_with_dict}
All frame APIs are not affected.
There are two affected use cases:
- decompressing LZ4 data with the
unsafeimplementation (safe-decodefeature flag disabled, which is enabled by default): can leak content of uninitialized memory as decompressed result - decompressing LZ4 data into a reused, user-supplied
outputbuffer (affects thesafe-decodefeature as well): can leak the previous contents of the output buffer as decompressed result
Impact
Leakage of data from uninitialized memory or content from previous decompression operations, possibly revealing sensitive information and secrets.
Mitigation
lz4_flex 0.12.1 and 0.11.6 fixes this issue without requiring changes in user code.
If you cannot upgrade, you can mitigate this vulnerability by zeroing the output buffer before calling block::decompress_into or block::decompress_into_with_dict (only block based API is affected, frame API is not affected). Additionally the the safe-decode feature flag should be enabled.
GitHub
CVSS SCORE
8.2high| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| lz4_flex | cargo | - | - | <0.11.6 | 0.11.6 |
| lz4_flex | cargo | - | - | >=0.12.0,<0.12.1 | 0.12.1 |
CVSS:4 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges.
There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
There is no loss of integrity within the Vulnerable System.
There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
There is no impact to availability within the Vulnerable System.
There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.