Freeradius: stack buffer overflow via unchecked eap-fast sessionticket length
Summary
| CVE | CVE-2026-127030 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-12 17:17:43 UTC |
| Updated | 2026-11-12 17:17:43 UTC |
| Description | A flaw was found in freeradius. An improper length validation in the EAP-FAST module allows a stack-based buffer overflow during session ticket processing. A remote, unauthenticated attacker can exploit this flaw by sending a specially crafted handshake request, causing the server process to crash and resulting in a Denial of Service (DoS). |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Problem Types: CWE-787 | CWE-787 Out-of-bounds Write
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| github.com/FreeRADIUS/freeradius-server/commit/a5d09dad528d7a3a3c4c01158... | [email protected] | github.com | |
| github.com/FreeRADIUS/freeradius-server/commit/064567a08f3b9d9b4863fab60... | [email protected] | github.com | |
| access.redhat.com/security/cve/CVE-2026-127030 | [email protected] | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank s4cr00t (Alipay Security Team) for reporting this issue. Upstream acknowledges Ada Logics and [email protected] as the original reporters. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-11-03T10:16:22.000Z | Reported to Red Hat. |
| CNA | 2026-11-12T12:12:02.163Z | Made public. |
Workarounds
CNA: Disable the EAP-FAST submodule in the FreeRADIUS configuration, or restrict incoming RADIUS traffic to trusted network access points. 1. Disable EAP-FAST: In `/etc/raddb/mods-available/eap` (or `/etc/raddb/eap.conf`), comment out the `fast` section within the `eap` configuration block and verify that `default_eap_type` is not set to `fast`. 2. Apply configuration changes: ``` systemctl restart radiusd ``` 3. Limit network exposure: Restrict UDP port 1812 to authorized Network Access Server (NAS) clients using firewalld: ``` firewall-cmd --permanent --zone=internal --add-source=<TRUSTED_IP_OR_SUBNET> firewall-cmd --permanent --zone=internal --add-port=1812/udp firewall-cmd --reload ``` Caveats: Disabling EAP-FAST prevents authentication for any network clients that rely exclusively on EAP-FAST. Restricting firewall rules will block traffic from unlisted authenticator sources. Warning: Restarting or reloading the radiusd service will temporarily disrupt active RADIUS authentication processing.