# CVE-2026-128885: Dbus: stack out-of-bounds write in dbus _dbus_poll() select() fallback when file descriptor exceeds fd_setsize

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

A flaw was found in D-Bus. In configurations where the daemon falls back to using the Unix select() mechanism for event monitoring, it does not verify whether file descriptor numbers exceed allocated limits. A local attacker can exploit this flaw by opening a large number of concurrent connections to trigger an out-of-bounds write on the stack. This can cause the daemon to crash, resulting in a Denial of Service (DoS).

## Remediation

- workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (dbus): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat

- CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-121

## Exploit evidence

- exploit: https://bugzilla.redhat.com/show_bug.cgi?id=2462795 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-128885 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2462795 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2462795 (ADP: CISA-ADP; exploit)

- https://access.redhat.com/security/cve/CVE-2026-128885 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2462795 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2462795 (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-128885; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-128885; retrieved 2026-11-14; source updated 2026-11-13

Revision: 632d6622fd35d4ea46b524685698c346df279245a81fd842bca8ac508031807c

Canonical: https://y2.dev/cve/CVE-2026-128885

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