Mailbox data spoofing via pre-STARTTLS response processing
Published Aug 5, 2021 · Updated Aug 3, 2024
Improper STARTTLS handling in Mozilla Thunderbird before 78.12 allows man-in-the-middle attackers to display false IMAP mailbox data. The IMAP connection logic processes server responses received before the STARTTLS handshake finishes instead of discarding the untrusted pre-encryption data. Exploitation requires Thunderbird to use STARTTLS and the attacker to inject traffic before encryption; the demonstrated consequence is false mailbox information, including nonexistent folders.
Summary
What happened
Improper STARTTLS handling in Mozilla Thunderbird before 78.12 allows man-in-the-middle attackers to display false IMAP mailbox data. The IMAP connection logic processes server responses received before the STARTTLS handshake finishes instead of discarding the untrusted pre-encryption data. Exploitation requires Thunderbird to use STARTTLS and the attacker to inject traffic before encryption; the demonstrated consequence is false mailbox information, including nonexistent folders.
The record
- CVE
- CVE-2021-29969
- Published
- Aug 5, 2021
- Updated
- Aug 3, 2024
- Vendor
- Mozilla
- Product
- Thunderbird
- Classifications
- CWE-552, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 5, 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
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <78.12
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
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo