CVE-2026-21908
HighSummary
A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved. An authenticated, network-adjacent attacker can flap a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code as root. The issue occurs during processing of a change of authorization (CoA) when a port bounce happens, where a freed pointer is later referenced.
Risk Assessment
The vulnerability allows an authenticated attacker on the local network to crash the dot1xd process, causing network service disruption (DoS). In the worst case, arbitrary code execution with root privileges is possible, giving full control over the device.
Recommendation
It is recommended to promptly update Junos OS or Junos OS Evolved to a patched version as per vendor guidance. If patching is not possible, consider restricting network access or disabling 802.1X PNAC on affected systems.
Other vulnerabilities in Juniper Junos OS
See all- CVE-2026-21906High
A vulnerability in the packet forwarding engine (PFE) of Junos OS on SRX Series allows an unauthenticated network-based attacker to send a specific ICMP packet through a GRE tunnel, causing the PFE to crash and restart. The issue occurs when PowerMode IPsec (PMI) and GRE performance acceleration are enabled, leading to traffic loss.
- CVE-2016-1278High
Junos OS versions before 12.1X46-D50 on SRX Series devices revert to 'safe mode' after a failed upgrade to 12.1X46, allowing root CLI logins without a password. This may allow local users to gain privileges by leveraging the 'request system software' command with the 'partition' option.
- CVE-2016-1271High
In Juniper Junos OS versions before 12.1X46-D45, 12.1X47-D30, 12.3R11, 12.3X48-D25, 13.2R8, 13.3R7, 14.1R6, 14.2R4, 15.1R1, 15.1F2, and 15.1X49-D15, a vulnerability allows local users to gain privileges via crafted combinations of CLI commands and arguments. This is a different vulnerability than CVE-2015-3003, CVE-2014-3816, and CVE-2014-0615.
- CVE-2016-1264High
A race condition in the Op command in Juniper Junos OS allows remote authenticated users to gain privileges via the URL option. This affects versions before 12.1X44-D55, 12.1X46 before 12.1X46-D40, 12.1X47 before 12.1X47-D25, and other listed versions.
- CVE-2014-6450High
In Juniper Junos OS versions before 11.4R12-S4, 12.1X44-D41, 12.1X46-D26, 12.1X47-D11/D15, 12.2R9, 12.2X50-D70, 12.3R8, 12.3X48-D10, 12.3X50-D42, 13.1R4-S3, 13.1X49-D42, 13.1X50-D30, 13.2R6, 13.2X51-D26, 13.2X52-D15, 13.3R3-S3, 14.1R3, 14.2R1, 15.1R1, and 15.1X49-D10, when configured for IPv6, remote attackers can cause a denial of service (mbuf chain corruption and kernel panic) via crafted IPv6 packets.
- CVE-2015-5359High
A vulnerability in Juniper Junos OS allows remote attackers to cause a denial of service by sending a large number of BGP-VPLS advertisements with updated BGP local preference values. This affects multiple versions of the OS before their respective patches.
- CVE-2015-5358High
A vulnerability in Juniper Junos OS allows remote attackers to cause a denial of service by sending a large number of requests, triggering a TCP connection to move to the LAST_ACK state while there is more data to send.
- CVE-2014-3818High
In Juniper Junos OS versions from 9.1 to 14.1 before specific updates, a vulnerability exists that allows remote attackers to cause a denial of service through crafted transitive attributes in a BGP UPDATE. This can lead to memory corruption and a crash and restart of the RDP routing process.
Original NVD description (English source)
A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root. The issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path. This issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled. This issue affects: Junos OS: * from 23.2R2-S1 before 23.2R2-S5, * from 23.4R2 before 23.4R2-S6, * from 24.2 before 24.2R2-S3, * from 24.4 before 24.4R2-S1, * from 25