A830r Firmware: Stack-based Buffer Overflow
CVE-2025-28029 is a high-severity stack-based buffer overflow vulnerability in A830r Firmware from TOTOLINK, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected A830r Firmware versions: 4.1.2cu.5182_b20201102. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.4% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of A830r Firmware you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TOTOLINK | A830r Firmware | 4.1.2cu.5182_b20201102 | Not stated |
| TOTOLINK | A950rg Firmware | 4.1.2cu.5161_b20200903 | Not stated |
| TOTOLINK | A3000ru Firmware | 5.9c.5185_b20201128 | Not stated |
| TOTOLINK | A3100r Firmware | 4.1.2cu.5247_b20211129 | Not stated |
Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- LowSome restricted data can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L. Scored by CISA (ADP).
Official description
TOTOLINK A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129 were found to contain a buffer overflow vulnerability in cstecgi.cgi
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Stack-based Buffer Overflow
The product writes past the end of a buffer that was allocated on the stack.
How developers prevent this class of flaw
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Implement and perform bounds checking on input.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- locrian-lightning-dc7.notion.site/BufferOverflow5-1978e5e2b1a28043af78e5ccfc0203a0Exploit, Third Party Advisory
- locrian-lightning-dc7.notion.site/CVE-2025-28023-CVE-2025-28029-BufferOverflow5-1978e5e2b1a28043af78e5ccfc020…Exploit, Third Party Advisory
Other vulnerabilities in A830r Firmware
- 7.3 High severity
- 7.3 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.3 High severity
- 7.3 High severity
Recent Stack-based Buffer Overflow vulnerabilities
- 8.8 High severity
- 7.3 High severity
- 7.3 High severity
- 7.3 High severity
- 9.8 Critical severity
- 8.2 High severity
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