Code execution via additive firmware checksum collision
Published Sep 2, 2025 · Updated Sep 2, 2025
Firmware integrity bypass in Tenda CP6 11.10.00.243 allows remote attackers to install malicious firmware through the update process. The uhttp function sub_2B7D04 validates update images with an additive checksum, allowing a crafted image with the same sum to pass verification. No privileges or user interaction are required, but producing a colliding image has high complexity; installation enables arbitrary code execution or a service interrupt.
Summary
What happened
Firmware integrity bypass in Tenda CP6 11.10.00.243 allows remote attackers to install malicious firmware through the update process. The uhttp function sub_2B7D04 validates update images with an additive checksum, allowing a crafted image with the same sum to pass verification. No privileges or user interaction are required, but producing a colliding image has high complexity; installation enables arbitrary code execution or a service interrupt.
The record
- CVE
- CVE-2025-9828
- Published
- Sep 2, 2025
- Updated
- Sep 2, 2025
- Vendor
- Shenzhen Tenda Technology Co., Ltd.
- Product
- CP6
- Classifications
- CWE-310, CWE-327, T1601.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 2, 2025CVE publishedPublication date reported by the CVE source.
- Sep 2, 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=11.10.00.243
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
- Additive-checksum firmware integrity bypassproof of concept · unverified
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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