# CVE-2026-124739: Busybox: httpd stack buffer overflow via an "i:" rule in a subdirectory httpd.conf

Status: published. Published: 2026-11-11. Updated: 2026-11-11.

A flaw was found in BusyBox. When the httpd web server processes subdirectory configuration files, an overly long index page name can trigger a stack-based buffer overflow. An attacker with permissions to write to a subdirectory configuration file could exploit this vulnerability to execute arbitrary code with elevated privileges or cause a denial of service (DoS) by crashing the server process.

## Remediation

- workaround: Prevent untrusted users from creating or modifying configuration files by restricting write permissions on all web root and subdirectory paths served by BusyBox httpd to administrative accounts only:

chmod -R o-w /path/to/webroot

Additionally, ensure the BusyBox httpd process drops elevated privileges by specifying an unprivileged user with the `-u` flag upon execution:

busybox httpd -u nobody

Restarting the daemon is required for process-level flag changes to take effect, which will temporarily terminate active network connections.

Caveats: Running under a non-privileged user account prevents binding directly to privileged ports (below 1024) without additional system capabilities or port forwarding, and restricting directory permissions may interfere with workflows that require unprivileged file uploads. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 6 (busybox): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (busybox): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: redhat

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2026-124739 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2571613 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-124739 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2571613 (secalert@redhat.com)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-124739; retrieved 2026-11-11; source updated 2026-11-11

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124739; retrieved 2026-11-11; source updated 2026-11-11

Revision: b971311f39b198a63e41148523f127291fd79f212c2fa89a5e1d15793e8ca670

Canonical: https://y2.dev/cve/CVE-2026-124739

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