Authenticated code-path execution via unchecked desc copy
Published Aug 30, 2026 · Updated Aug 30, 2026
Stack-based buffer overflow in TOTOLINK A720R 4.1.5cu.630_B20250509 allows remote authenticated users to execute code paths. The setMacFilterRules handler in cstecgi.cgi copies an oversized desc parameter with strcpy into a fixed-size stack buffer, overwriting the saved return address. Administrator credentials and network access are required; successful exploitation can reboot the router, clear logs, end sessions, or enable Telnet.
Summary
What happened
Stack-based buffer overflow in TOTOLINK A720R 4.1.5cu.630_B20250509 allows remote authenticated users to execute code paths. The setMacFilterRules handler in cstecgi.cgi copies an oversized desc parameter with strcpy into a fixed-size stack buffer, overwriting the saved return address. Administrator credentials and network access are required; successful exploitation can reboot the router, clear logs, end sessions, or enable Telnet.
The record
- CVE
- CVE-2026-82539
- Published
- Aug 30, 2026
- Updated
- Aug 30, 2026
- Vendor
- TOTOLINK
- Product
- A720R
- Classifications
- CWE-119, T1499.004
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Aug 30, 2026CVE publishedPublication date reported by the CVE source.
- Aug 30, 2026Record 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=4.1.5cu.630_B20250509
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
- Xernary A720R setMacFilterRules proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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