hostapd: Off-by-one Error
CVE-2026-58374 is a high-severity off-by-one error vulnerability in hostapd from W1.fi, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists version 2.12 as the first without the flaw, so updating hostapd to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.29% 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 hostapd to 2.12 or a later version.
Affected products and versions
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.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.5 | Medium | CNA (mitre.org) |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
In hostapd before 2.12, a missing bounds check in AP-mode Wi-Fi 7 (IEEE 802.11be) Multi-Link Operation (MLO) association request processing allows an unauthenticated attacker within wireless range to send a crafted management frame containing a malformed Multi-Link Element or Per-STA Profile subelement. In hostapd_process_ml_assoc_req() in src/ap/ieee802_11_eht.c, the received link_id field can be parsed as value 15, but the corresponding links[] storage only has valid entries for lower link IDs (0 through 14). This causes an out-of-bounds write / small memory corruption during association processing before the 4-way handshake. The attack does not require network credentials, prior authentication, or user interaction. The confirmed practical impact is denial of service through hostapd process termination. This affects hostapd v2.11 and newer development snapshots before v2.12 when built with CONFIG_IEEE80211BE enabled. The issue is fixed in hostapd v2.12 and the upstream 2026-1 fixes.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Off-by-one Error
A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.
How developers prevent this class of flaw
- When copying character arrays or using character manipulation methods, the correct size parameter must be used to account for the null terminator that needs to be added at the end of the array. Some examples of functions susceptible to this weakness in C include strcpy(), strncpy(), strcat(), strncat(), printf(), sprintf(), scanf() and sscanf().
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.w1.fi/cgit/hostap/commit/?id=46dd5a4ffc9bcf44cf8fc45120b3e1e5ec922187
- git.w1.fi/cgit/hostap/commit/?id=aa9d345887389a251c63a3781d2ad2940d079193
- w1.fi/security/2026-1/missing-ml-parsing-validation.txtMitigation, Third Party Advisory
- openwall.com/lists/oss-security/2026/06/30/1Mailing List, Mitigation
Other references
- w1.fi/security/2026-1/Issue Tracking
Other vulnerabilities in hostapd
- 9.8 Critical severity
- 9.8 Critical severity
Recent Off-by-one Error vulnerabilities
- 8.6 High severity
- 9.8 Critical severity
- 7.3 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
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