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CVE-2026-15893— Zephyr IPv6 Neighbor Discovery zero reachable time from crafted Router Advertisement causes assertion/DoS

Quick assessment

Affected
zephyrproject zephyr
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

zephyrproject Zephyr是zephyrproject组织开源的一款面向物联网设备的实时操作系统。 zephyrproject Zephyr 1.7.0版本至4.4.2之前版本存在异常处理不当漏洞，该漏洞源于net_if_ipv6_calc_reachable_time()函数在base_reachable_time为1时计算错误返回0，攻击者可通过未经身份验证的链路本地Router Advertisement将Reachable Time设为1，导致内核断言触发或邻居发现降级，造成拒绝服务

CVSS 6.5 · Medium EPSS 0.33% · P26

Possible ATT&CK Techniques 1 AI

T1527

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 1.7.0< 4.4.2 affected
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I. Basic Information for CVE-2026-15893

Vulnerability Information
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Vulnerability Title
Zephyr IPv6 Neighbor Discovery zero reachable time from crafted Router Advertisement causes assertion/DoS
Source: CVE Program / CVE List V5
Vulnerability Description
net_if_ipv6_calc_reachable_time() in subsys/net/ip/net_if.c derives a randomized ND reachable time from ipv6->base_reachable_time as min_reachable + sys_rand32_get() % (max_reachable - min_reachable), where min_reachable = base/2 and max_reachable = 3*base/2 using integer division. When base_reachable_time is 1, both min_reachable and the modulus collapse so the function returns 0, and net_if_ipv6_set_reachable_time() stores that 0 into ipv6->reachable_time. The base_reachable_time is attacker-controlled: handle_ra_input() in subsys/net/ip/ipv6_nbr.c accepts the Reachable Time field of an incoming Router Advertisement whenever it is nonzero and <= MAX_REACHABLE_TIME, so a single unauthenticated, link-local RA carrying a Reachable Time of 1 drives the computed reachable time to 0. Router Advertisements are unauthenticated by default and require only adjacency to the target link. When a neighbor is subsequently confirmed reachable, net_ipv6_nbr_set_reachable_timer() reads the value and executes NET_ASSERT(time, "Zero reachable timeout!"). On builds with CONFIG_ASSERT enabled this triggers a fatal kernel assertion — a remote denial of service; on builds without assertions the reachable timer is armed with K_MSEC(0) and fires immediately, forcing reachable neighbors into perpetual re-solicitation (STALE), degrading Neighbor Discovery. The impact is limited to availability; there is no memory-safety, confidentiality, or integrity consequence.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
可达断言
Source: CVE Program / CVE List V5
Vulnerability Title
zephyrproject Zephyr 异常处理不当漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
zephyrproject Zephyr是zephyrproject组织开源的一款面向物联网设备的实时操作系统。 zephyrproject Zephyr 1.7.0版本至4.4.2之前版本存在异常处理不当漏洞，该漏洞源于net_if_ipv6_calc_reachable_time()函数在base_reachable_time为1时计算错误返回0，攻击者可通过未经身份验证的链路本地Router Advertisement将Reachable Time设为1，导致内核断言触发或邻居发现降级，造成拒绝服务
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
zephyrproject zephyr 1.7.0 ~ 4.3.2 -

II. Public POCs for CVE-2026-15893

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III. Intelligence Information for CVE-2026-15893

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Patches & Fixes for CVE-2026-15893 (1)

Vendor Advisories for CVE-2026-15893 (1)

Same Patch Batch · zephyrproject · 2026-09-14 · 6 CVEs total

CVE-2026-16147 6.8 MEDIUM it82xx2 USB device controller submits incomplete OUT transfer buffers, causing use-after-f
CVE-2026-14986 6.8 MEDIUM Out-of-bounds write in it51xxx I2C target FIFO ISR on oversized write transaction
CVE-2026-15924 5.9 MEDIUM Use-after-free / double-free from unsynchronized concurrent access to the TLS client sessi
CVE-2026-15923 4.6 MEDIUM Infinite loop denial of service in Zephyr SDIO byte-I/O from a card-supplied zero max_blk_
CVE-2026-16148 4.6 MEDIUM Kernel panic in the it82xx2 USB device controller driver via re-initialization of a busy d

IV. Related Vulnerabilities

Same product: zephyr
Same vendor: zephyrproject
Same weakness: CWE-617