Archer C5 v6.8: Improper Neutralization of Input During Web Page Generation
CVE-2026-8699 is a high-severity improper neutralization of input during web page generation vulnerability in Archer C5 v6.8 from TP-Link, with a CVSS 4.0 base score of 7.0 out of 10. It can be exploited from the same local network by an attacker with administrator privileges, but only if a user takes part, for example by opening a link or file. The record lists version 0.2.0 3.0.0 v6063.0 Build 260331 Rel.37416n as the first without the flaw, so updating Archer C5 v6.8 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.28% 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
- Update Archer C5 v6.8 to 0.2.0 3.0.0 v6063.0 Build 260331 Rel.37416n or a later version.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TP-Link | Archer C5 v6.8 | before 0.2.0 3.0.0 v6063.0 Build 260331 Rel.37416n | 0.2.0 3.0.0 v6063.0 Build 260331 Rel.37416n |
Version data comes from the organisation that assigned the CVE. 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.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- HighAdministrator-level access is required first.
- User interaction
- ActiveA user must deliberately do something unusual, such as dismissing a warning.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA.
Official description
A stored Cross-Site Scripting (XSS) vulnerability has been identified in the web-based management interface of Archer C5 v6.8 routers, due to insufficient server-side validation and lack of proper output encoding of user-controlled input in a certain field. An attacker with administrative privileges can inject crafted HTML or JS payloads into the affected field. The payload is stored and later executed when the affected page is rendered in an administrator's browser.Successful exploitation allows execution of arbitrary JavaScript in an admin's browser, potentially leading to session hijacking and unauthorized access to router configuration, possibly resulting in exposure of sensitive data and modification of device settings. The vulnerability affects ISP-managed firmware variants of the product. Remediation is coordinated through service providers.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Input During Web Page Generation
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
How developers prevent this class of flaw
- 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 of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
- Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Improper Neutralization of Input During Web Page Generation vulnerabilities (CWE-79)
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
Other references
Recent Improper Neutralization of Input During Web Page Generation vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 7.4 High severity
- 7.3 High severity
- 7.2 High severity
- 7.6 High severity
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