# CVE-2026-85234: Tftp: tftp-hpa: denial of service due to out-of-bounds read/write in remap engine

Status: published. Published: 2026-09-15. Updated: 2026-11-06.

A flaw was found in tftp-hpa. When the `in.tftpd` remap engine processes an inverse remap rule that also aborts with a non-empty custom error message, it can pass invalid match offsets to the `genmatchstring()` function. This leads to out-of-bounds read/write operations. A remote, unauthenticated attacker can exploit this vulnerability by sending a specially crafted request, causing the daemon to crash and resulting in a denial of service.

## Remediation

- workaround: To mitigate this issue, avoid enabling filename remapping with the `m/-map-file` option for the `in.tftpd` service unless strictly necessary. If filename remapping is required, ensure that any inverse (`~`) and abort (`a`) rules in the remap file do not include a non-empty custom error message. Changes to the `in.tftpd` configuration may require restarting the service to take effect. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (tftp): ≥ 0:5.2-50.el10_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (tftp): ≥ 0:5.2-28.el8_10; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (tftp): ≥ 0:5.2-40.el9_8.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (tftp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (tftp): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (erlang27): Version range not reported. Source: CNA: redhat

## Severity and prioritization

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

- CISA KEV: No listing in collected sources

- EPSS: 0.47% as of 2026-11-05; percentile 40.78%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125

## Exploit evidence

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

## References

- https://access.redhat.com/errata/RHSA-2026:78952 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:80663 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82280 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-85234 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2460997 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://git.kernel.org/pub/scm/network/tftp/tftp-hpa.git/commit/?id=4b493532f5ce052a1c124acd0661233ec7918327 (CNA: redhat)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-85234; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-85234; retrieved 2026-11-06; source updated Not reported

Revision: 459984077d78bc86a53ec1121eba8b801f76286142ca9990f5549255886802aa

Canonical: https://y2.dev/cve/CVE-2026-85234

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