Kernel-memory disclosure via unterminated SMB transaction name
Published Oct 19, 2021 · Updated Aug 3, 2024
Out-of-bounds read in SMB on Apple macOS before Big Sur 11.6 allows remote attackers to disclose kernel memory through an SMB connection. The smb_usr_t2request path copies an attacker-controlled transaction name without a terminating null byte, and smb_put_dstring then uses strlen to read adjacent heap data into an outbound SMB packet. Exploitation requires the Mac to connect to an attacker-controlled SMB server, which receives the disclosed kernel-memory bytes.
Summary
What happened
Out-of-bounds read in SMB on Apple macOS before Big Sur 11.6 allows remote attackers to disclose kernel memory through an SMB connection. The smb_usr_t2request path copies an attacker-controlled transaction name without a terminating null byte, and smb_put_dstring then uses strlen to read adjacent heap data into an outbound SMB packet. Exploitation requires the Mac to connect to an attacker-controlled SMB server, which receives the disclosed kernel-memory bytes.
The record
- CVE
- CVE-2021-30844
- Published
- Oct 19, 2021
- Updated
- Aug 3, 2024
- Vendor
- Apple
- Product
- macOS
- Classifications
- CWE-401
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Oct 19, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <11.6
- Affected versionversion=unspecified <2021
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- macOS smbfs out-of-bounds-read proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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