CVE-2021-0217
Published: 15 January 2021
Summary
CVE-2021-0217 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Juniper Junos. Its CVSS base score is 7.4 (High).
Operationally, ranked at the 28.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-2836
Vulnerability details
A vulnerability in processing of certain DHCP packets from adjacent clients on EX Series and QFX Series switches running Juniper Networks Junos OS with DHCP local/relay server configured may lead to exhaustion of DMA memory causing a Denial of Service…
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(DoS). Over time, exploitation of this vulnerability may cause traffic to stop being forwarded, or to crashing of the fxpc process. When Packet DMA heap utilization reaches 99%, the system will become unstable. Packet DMA heap utilization can be monitored through the following command: user@junos# request pfe execute target fpc0 timeout 30 command "show heap" ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 213301a8 536870488 387228840 149641648 27 Kernel 1 91800000 8388608 3735120 4653488 55 DMA 2 92000000 75497472 74452192 1045280 1 PKT DMA DESC 3 d330000 335544320 257091400 78452920 23 Bcm_sdk 4 96800000 184549376 2408 184546968 99 Packet DMA <--- 5 903fffe0 20971504 20971504 0 0 Blob An indication of the issue occurring may be observed through the following log messages: Dec 10 08:07:00.124 2020 hostname fpc0 brcm_pkt_buf_alloc:523 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.126 2020 hostname fpc0 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.128 2020 hostname fpc0 brcm_pkt_buf_alloc:523 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.130 2020 hostnameC fpc0 (buf alloc) failed allocating packet buffer This issue affects Juniper Networks Junos OS on EX Series and QFX Series: 17.4R3 versions prior to 17.4R3-S3; 18.1R3 versions between 18.1R3-S6 and 18.1R3-S11; 18.2R3 versions prior to 18.2R3-S6; 18.3R3 versions prior to 18.3R3-S4; 18.4R2 versions prior to 18.4R2-S5; 18.4R3 versions prior to 18.4R3-S6; 19.1 versions between 19.1R2 and 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2. Junos OS versions prior to 17.4R3 are unaffected by this vulnerability.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
This control implements explicit throttling on session allocation, addressing the weakness of allocating resources without limits.
Plan testing exercises resource allocation limits and throttling during simulated failures, directly addressing weaknesses that allow unbounded resource use.
Contingency plan updates ensure recovery strategies address unbounded resource allocation, making it harder for attackers to exploit lack of throttling to cause prolonged outages.
Provides continuity when unbounded resource allocation at the primary site leads to exhaustion and downtime.
Alternate services allow operations to continue when primary allocation of resources lacks limits or throttling.
Explicit planning of security-related actions requires defining limits, windows, and resource allocations, making allocation without throttling far less likely.
Measures of performance include tracking allocation behavior and throttling effectiveness, reducing the window for resource exhaustion attacks.
Ongoing control assessments and code testing (static/dynamic analysis, fuzzing) surface memory buffer restriction failures, which are then remediated before release.