Code execution via mismatched message length fields
Published Nov 24, 2021 · Updated Sep 17, 2024
Classic buffer overflow in affected Zoom products allows remote attackers to crash processes or execute code through crafted message traffic. In ssb::conf_send_msg_req::load_from, one attacker-controlled length allocates a heap buffer while read_str_with_len uses a second length to copy up to 0x1FFF bytes into it. The sender must reach a client through Zoom messaging or meeting traffic; MMR-side triggering occurs during a Zoom Webinar.
Summary
What happened
Classic buffer overflow in affected Zoom products allows remote attackers to crash processes or execute code through crafted message traffic. In ssb::conf_send_msg_req::load_from, one attacker-controlled length allocates a heap buffer while read_str_with_len uses a second length to copy up to 0x1FFF bytes into it. The sender must reach a client through Zoom messaging or meeting traffic; MMR-side triggering occurs during a Zoom Webinar.
The record
- CVE
- CVE-2021-34423
- Published
- Nov 24, 2021
- Updated
- Sep 17, 2024
- Vendor
- Zoom Video Communications, Inc.
- Product
- Zoom Meeting SDK for macOS
- Classifications
- CWE-120, T1203, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 24, 2021CVE publishedPublication date reported by the CVE source.
- Sep 17, 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 <5.7.6.1340
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
- Project Zero malformed Zoom message proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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