Terminal hang via malformed OSC 8 sequence
Published Feb 7, 2023 · Updated Mar 25, 2025
Improper ANSI sequence filtering in GNU less 566 through 608 allows remote attackers to hang terminals through crafted input. The ansi_step state machine in line.c treats an ESC byte followed by a non-backslash character as an unfinished OSC 8 hyperlink instead of rejecting the malformed terminator, allowing terminal control bytes to pass through. The user must open attacker-controlled data with less -R; a malicious sequence can induce a terminal reply loop that repeatedly scrolls and echoes data.
Summary
What happened
Improper ANSI sequence filtering in GNU less 566 through 608 allows remote attackers to hang terminals through crafted input. The ansi_step state machine in line.c treats an ESC byte followed by a non-backslash character as an unfinished OSC 8 hyperlink instead of rejecting the malformed terminator, allowing terminal control bytes to pass through. The user must open attacker-controlled data with less -R; a malicious sequence can induce a terminal reply loop that repeatedly scrolls and echoes data.
The record
- CVE
- CVE-2022-46663
- Published
- Feb 7, 2023
- Updated
- Mar 25, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 7, 2023CVE publishedPublication date reported by the CVE source.
- Mar 25, 2025Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- Terminal reply-loop proof of conceptproof of concept · demonstrated
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Technologies
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Your stack
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