Memory corruption via truncated percent escape
Published Aug 5, 2022 · Updated Apr 15, 2025
Out-of-bounds write in httpd unescape in Asuswrt-Merlin New Gen before 386.7 allows remote attackers to corrupt memory via HTTP. The cgi.c unescape function assumes every percent sign has two following hex characters, then copies from beyond a short escape and can remove the string terminator. No authentication or user interaction is required; a crafted network request can write beyond the intended buffer, while Talos reports no confidentiality or availability impact.
Summary
What happened
Out-of-bounds write in httpd unescape in Asuswrt-Merlin New Gen before 386.7 allows remote attackers to corrupt memory via HTTP. The cgi.c unescape function assumes every percent sign has two following hex characters, then copies from beyond a short escape and can remove the string terminator. No authentication or user interaction is required; a crafted network request can write beyond the intended buffer, while Talos reports no confidentiality or availability impact.
The record
- CVE
- CVE-2022-26376
- Published
- Aug 5, 2022
- Updated
- Apr 15, 2025
- Vendor
- Asuswrt-Merlin
- Product
- Asuswrt-Merlin New Gen
- Classifications
- CWE-787, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 5, 2022CVE publishedPublication date reported by the CVE source.
- Apr 15, 2025Record 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=prior to 386.7
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.
Public exploit references
- Cisco Talos truncated percent-escape demonstrationproof 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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