- Reported
-
- Issued
-
- Package
-
lz4_flex
(crates.io)
- Type
-
Vulnerability
- Categories
-
- Keywords
-
#lz4
#decompression
#information-disclosure
#uninitialized-memory
- Aliases
-
- CVSS Score
- 8.2
HIGH
- CVSS Details
-
- Attack Complexity
- Low
- Attack Requirements
- Present
- Attack Vector
- Network
- Privileges Required
- None
- Availability Impact to the Subsequent System
- None
- Confidentiality Impact to the Subsequent System
- None
- Integrity Impact to the Subsequent System
- None
- User Interaction
- None
- Availability Impact to the Vulnerable System
- None
- Confidentiality Impact to the Vulnerable System
- High
- Integrity Impact to the Vulnerable System
- None
- CVSS Vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- Patched
-
>=0.11.6, <0.12.0>=0.12.1
- Affected Functions
- Version
lz4_flex::block::decompress_into-
lz4_flex::block::decompress_into_with_dict-
Description
Decompressing invalid LZ4 data with the block API can leak data from uninitialized memory,
or leak content from previous decompression operations when reusing an output buffer.
The LZ4 block format defines a "match copy operation" which duplicates previously written
data or data from a user-supplied dict. The position of that data is defined by an offset.
lz4_flex did not properly validate offset values, causing it to copy data from outside
the initialized portion of the output buffer.
Two scenarios are affected:
- Decompressing with the
unsafe implementation (safe-decode feature flag disabled, which
is the default): can leak content of uninitialized memory as part of the decompressed result.
- Decompressing into a reused, user-supplied output buffer (also affects
safe-decode): can
leak the previous contents of the output buffer as part of the decompressed result.
Only the block-based API is affected: lz4_flex::block::decompress_into and
lz4_flex::block::decompress_into_with_dict. All frame APIs are unaffected.
The flaw was corrected in versions 0.11.6 and 0.12.1 by properly validating offset values
during decompression.
If upgrading is not possible, the issue can be mitigated by zeroing the output buffer before
each call to the affected functions and enabling the safe-decode feature flag.
Advisory available under CC0-1.0
license.