CVE-2021-1387

Cisco NX-OS Software IPv6 Netstack Denial of Service Vulnerability

HIGH

8.6

CVSS Score

Published: February 24, 2021 at 07:30 PM UTC

Updated: June 17, 2026 at 03:31 AM UTC

121 products affected across 1 vendorNx OSUnified Computing SystemNexus 9508

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Severity

HIGH8.6

Exploit prediction

EPSS 1%

SSVC

No known exploit

Description

A vulnerability in the network stack of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because the software improperly releases resources when it processes certain IPv6 packets that are destined to an affected device. An attacker could exploit this vulnerability by sending multiple crafted IPv6 packets to an affected device. A successful exploit could cause the network stack to run out of available buffers, impairing operations of control plane and management plane protocols and resulting in a DoS condition. Manual intervention would be required to restore normal operations on the affected device. For more information about the impact of this vulnerability, see the Details section of this advisory.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Nx OS · Cisconpm

95%

6.0(2)a3(1)6.0(2)a3(2)6.0(2)a3(4)6.0(2)a4(1)6.0(2)a4(2)6.0(2)a4(3)6.0(2)a4(4)6.0(2)a4(5)6.0(2)a4(6)6.0(2)a6(1)6.0(2)a6(1a)6.0(2)a6(2)6.0(2)a6(2a)6.0(2)a6(3)6.0(2)a6(3a)6.0(2)a6(4)6.0(2)a6(4a)6.0(2)a6(5)6.0(2)a6(5a)6.0(2)a6(5b)6.0(2)a6(6)6.0(2)a6(7)6.0(2)a6(8)6.0(2)a7(1)6.0(2)a7(1a)6.0(2)a7(2)6.0(2)a7(2a)6.0(2)a8(1)6.0(2)a8(10)6.0(2)a8(10a)6.0(2)a8(11)6.0(2)a8(11a)6.0(2)a8(11b)6.0(2)a8(2)6.0(2)a8(3)6.0(2)a8(4)6.0(2)a8(4a)6.0(2)a8(5)6.0(2)a8(6)6.0(2)a8(7)6.0(2)a8(7a)6.0(2)a8(7b)6.0(2)a8(8)6.0(2)a8(9)6.0(2)u2(1)6.0(2)u2(2)6.0(2)u2(3)6.0(2)u2(4)6.0(2)u2(5)6.0(2)u2(6)6.0(2)u3(1)6.0(2)u3(2)6.0(2)u3(3)6.0(2)u3(4)6.0(2)u3(5)6.0(2)u3(6)6.0(2)u3(7)6.0(2)u3(8)6.0(2)u3(9)6.0(2)u4(1)6.0(2)u4(2)6.0(2)u4(3)6.0(2)u4(4)6.0(2)u5(1)6.0(2)u5(2)6.0(2)u5(3)6.0(2)u5(4)6.0(2)u6(1)6.0(2)u6(10)6.0(2)u6(10a)6.0(2)u6(1a)6.0(2)u6(2)6.0(2)u6(2a)6.0(2)u6(3)6.0(2)u6(3a)6.0(2)u6(4)6.0(2)u6(4a)6.0(2)u6(5)6.0(2)u6(5a)6.0(2)u6(5b)6.0(2)u6(5c)6.0(2)u6(6)6.0(2)u6(7)6.0(2)u6(8)6.0(2)u6(9)7.0(0)n1(1)7.0(1)n1(1)7.0(2)n1(1)7.0(3)f1(1)7.0(3)f2(1)7.0(3)f2(2)7.0(3)f3(1)7.0(3)f3(2)7.0(3)f3(3)7.0(3)f3(3a)7.0(3)f3(3c)7.0(3)f3(4)7.0(3)f3(5)7.0(3)i2(1)7.0(3)i2(1a)7.0(3)i2(2)7.0(3)i2(2a)7.0(3)i2(2b)7.0(3)i2(2c)7.0(3)i2(2d)7.0(3)i2(2e)7.0(3)i2(2r)7.0(3)i2(2s)7.0(3)i2(2v)7.0(3)i2(2w)7.0(3)i2(2x)7.0(3)i2(2y)7.0(3)i2(3)7.0(3)i2(4)7.0(3)i2(5)7.0(3)i3(1)7.0(3)i4(1)7.0(3)i4(1t)7.0(3)i4(2)7.0(3)i4(3)7.0(3)i4(4)7.0(3)i4(5)7.0(3)i4(6)7.0(3)i4(6t)7.0(3)i4(7)7.0(3)i4(8)7.0(3)i4(8a)7.0(3)i4(8b)7.0(3)i4(8z)7.0(3)i4(9)7.0(3)i5(1)7.0(3)i5(2)7.0(3)i5(3)7.0(3)i5(3a)7.0(3)i5(3b)7.0(3)i6(1)7.0(3)i6(2)7.0(3)i7(1)7.0(3)i7(2)7.0(3)i7(3)7.0(3)i7(3z)7.0(3)i7(4)7.0(3)i7(5)7.0(3)i7(5a)7.0(3)i7(6)7.0(3)i7(6z)7.0(3)i7(7)7.0(3)i7(8)7.0(3)ia7(1)7.0(3)ia7(2)7.0(3)ic4(4)7.0(3)im3(1)7.0(3)im3(2)7.0(3)im3(2a)7.0(3)im3(2b)7.0(3)im3(3)7.0(3)im7(2)7.0(3)n1(1)7.0(4)n1(1)7.0(4)n1(1a)7.0(5)n1(1)7.0(5)n1(1a)7.0(6)n1(1)7.0(6)n1(2s)7.0(6)n1(3s)7.0(6)n1(4s)7.0(7)n1(1)7.0(7)n1(1a)7.0(7)n1(1b)7.0(8)n1(1)7.0(8)n1(1a)7.1(0)n1(1)7.1(0)n1(1a)7.1(0)n1(1b)7.1(1)n1(1)7.1(1)n1(1a)7.1(2)n1(1)7.1(2)n1(1a)7.1(3)n1(1)7.1(3)n1(2)7.1(3)n1(2a)7.1(3)n1(3)7.1(3)n1(4)7.1(3)n1(5)7.1(4)n1(1)7.1(4)n1(1a)7.1(4)n1(1c)7.1(4)n1(1d)7.1(5)n1(1)7.1(5)n1(1b)7.2(0)d1(1)7.2(0)n1(1)7.2(1)d1(1)7.2(1)n1(1)7.2(2)d1(1)7.2(2)d1(2)7.2(2)d1(3)7.2(2)d1(4)7.3(0)d1(1)7.3(0)dx(1)7.3(0)n1(1)7.3(0)n1(1a)7.3(0)n1(1b)7.3(1)d1(1)7.3(1)n1(1)7.3(2)d1(1)7.3(2)d1(1d)7.3(2)d1(2)7.3(2)d1(3)7.3(2)d1(3a)7.3(2)n1(1)7.3(2)n1(1b)7.3(2)n1(1c)7.3(3)d1(1)7.3(3)n1(1)7.3(4)d1(1)7.3(4)n1(1)7.3(4)n1(1a)7.3(5)d1(1)7.3(5)n1(1)7.3(6)d1(1)7.3(6)n1(1)7.3(6)n1(1a)7.3(7)n1(1)7.3(7)n1(1a)7.3(7)n1(1b)8.0(1)8.1(1)8.1(2)8.1(2a)8.2(1)8.2(2)8.2(3)8.2(4)8.2(5)8.3(1)8.3(2)8.4(1)8.4(2)

cisco-nexus-3016 (environment) · cisco-nexus-3016q (environment) · cisco-nexus-3048 (environment) · cisco-nexus-3064 (environment) · cisco-nexus-3064-32t (environment) · cisco-nexus-3064-t (environment) · cisco-nexus-3064-x (environment) · cisco-nexus-3064t (environment) · cisco-nexus-3064x (environment) · cisco-nexus-3100-v (environment) · cisco-nexus-3100-z (environment) · cisco-nexus-3100v (environment) · cisco-nexus-31108pc-v (environment) · cisco-nexus-31108pv-v (environment) · cisco-nexus-31108tc-v (environment) · cisco-nexus-31128pq (environment) · cisco-nexus-3132c-z (environment) · cisco-nexus-3132q (environment) · cisco-nexus-3132q-v (environment) · cisco-nexus-3132q-x (environment) · cisco-nexus-3132q-xl (environment) · cisco-nexus-3164q (environment) · cisco-nexus-3172 (environment) · cisco-nexus-3172pq (environment) · cisco-nexus-3172pq-xl (environment) · cisco-nexus-3172tq (environment) · cisco-nexus-3172tq-32t (environment) · cisco-nexus-3172tq-xl (environment) · cisco-nexus-3232c (environment) · cisco-nexus-3264c-e (environment) · cisco-nexus-3264q (environment) · cisco-nexus-3408-s (environment) · cisco-nexus-34180yc (environment) · cisco-nexus-34200yc-sm (environment) · cisco-nexus-3432d-s (environment) · cisco-nexus-3464c (environment) · cisco-nexus-3524 (environment) · cisco-nexus-3524-x (environment) · cisco-nexus-3524-xl (environment) · cisco-nexus-3548 (environment) · cisco-nexus-3548-x (environment) · cisco-nexus-3548-xl (environment) · cisco-nexus-36180yc-r (environment) · cisco-nexus-3636c-r (environment) · cisco-nexus-5548p (environment) · cisco-nexus-5548up (environment) · cisco-nexus-5596t (environment) · cisco-nexus-5596up (environment) · cisco-nexus-56128p (environment) · cisco-nexus-5624q (environment) · cisco-nexus-5648q (environment) · cisco-nexus-5672up (environment) · cisco-nexus-5672up-16g (environment) · cisco-nexus-5696q (environment) · cisco-nexus-6001 (environment) · cisco-nexus-6001p (environment) · cisco-nexus-6001t (environment) · cisco-nexus-6004 (environment) · cisco-nexus-6004x (environment) · cisco-nexus-7000 (environment) · cisco-nexus-7004 (environment) · cisco-nexus-7009 (environment) · cisco-nexus-7010 (environment) · cisco-nexus-7018 (environment) · cisco-nexus-7700 (environment) · cisco-nexus-7702 (environment) · cisco-nexus-7706 (environment) · cisco-nexus-7710 (environment) · cisco-nexus-7718 (environment) · cisco-nexus-9000v (environment) · cisco-nexus-92160yc-switch (environment) · cisco-nexus-92160yc-x (environment) · cisco-nexus-9221c (environment) · cisco-nexus-92300yc (environment) · cisco-nexus-92304qc (environment) · cisco-nexus-92348gc-x (environment) · cisco-nexus-9236c (environment) · cisco-nexus-9272q (environment) · cisco-nexus-93108tc-ex (environment) · cisco-nexus-93108tc-ex-24 (environment) · cisco-nexus-93108tc-fx (environment) · cisco-nexus-93108tc-fx-24 (environment) · cisco-nexus-93108tc-fx3p (environment) · cisco-nexus-93120tx (environment) · cisco-nexus-93128 (environment) · cisco-nexus-93128tx (environment) · cisco-nexus-9316d-gx (environment) · cisco-nexus-93180lc-ex (environment) · cisco-nexus-93180tc-ex (environment) · cisco-nexus-93180yc-ex (environment) · cisco-nexus-93180yc-ex-24 (environment) · cisco-nexus-93180yc-fx (environment) · cisco-nexus-93180yc-fx-24 (environment) · cisco-nexus-93180yc-fx3 (environment) · cisco-nexus-93180yc-fx3s (environment) · cisco-nexus-93216tc-fx2 (environment) · cisco-nexus-93240yc-fx2 (environment) · cisco-nexus-9332c (environment) · cisco-nexus-9332pq (environment) · cisco-nexus-93360yc-fx2 (environment) · cisco-nexus-9336c-fx2 (environment) · cisco-nexus-9336c-fx2-e (environment) · cisco-nexus-9336pq (environment) · cisco-nexus-9348gc-fxp (environment) · cisco-nexus-93600cd-gx (environment) · cisco-nexus-9364c (environment) · cisco-nexus-9364c-gx (environment) · cisco-nexus-9372px (environment) · cisco-nexus-9372px-e (environment) · cisco-nexus-9372tx (environment) · cisco-nexus-9372tx-e (environment) · cisco-nexus-9396px (environment) · cisco-nexus-9396tx (environment) · cisco-nexus-9500r (environment) · cisco-nexus-9504 (environment) · cisco-nexus-9508 (environment) · cisco-nexus-9516 (environment)

Unified Computing System · Cisco

95%

4.0 ≤ v < 4.0(4k)4.1 ≤ v < 4.1(1e)

Affected range stops below 4.0(4k), so it looks safe — our inference, not a vendor statement

Affected range stops below 4.1(1e), so it looks safe — our inference, not a vendor statement

cisco-ucs-64108 (environment) · cisco-ucs-6454 (environment)

Nexus 3016 · Ciscodevice

80%

All versions

Nexus 3016Q · Ciscodevice

80%

All versions