Tl-wr940n Firmware: Buffer Copy without Checking Size of Input
CVE-2024-54887 is a high-severity buffer copy without checking size of input vulnerability in Tl-wr940n Firmware from TP-Link, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited from the same local network by an attacker with a low-privileged account, without any action from a user. Affected Tl-wr940n Firmware versions: 3.16.9 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 6.58% chance of exploitation within 30 days, which is in the top 6.07% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Tl-wr940n Firmware you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TP-Link | Tl-wr940n Firmware | 3.16.9 and earlier | 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
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CISA (ADP).
Official description
TP-Link TL-WR940N V3 and V4 with firmware 3.16.9 and earlier contain a buffer overflow via the dnsserver1 and dnsserver2 parameters at /userRpm/Wan6to4TunnelCfgRpm.htm. This vulnerability allows an authenticated attacker to execute arbitrary code on the remote device in the context of the root user.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Buffer Copy without Checking Size of Input
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- 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.
More Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- github.com/JBince/vulnerability-research/tree/main/CVE-2024-54887Third Party Advisory
Other vulnerabilities in Tl-wr940n Firmware
- 7.2 High severity
- 7.2 High severity
- 8.2 High severity
- 6.5 Medium severity
- 7.5 High severity
- 7.7 High severity
Recent Buffer Copy without Checking Size of Input vulnerabilities
- 7.9 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.3 Critical severity
- 7.5 High severity
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