DF-0343

IPv6 address configured while interface is down bypasses Duplicate Address Detection entirely

Summary

in6_update_ifa(:1074-1077) only sets IN6_IFF_TENTATIVE when in6if_do_dad true (requires IFF_UP+IFF_RUNNING, :2446). Address added while down: never tentative. in6_if_up_dispatch(:2406) only DADs tentative addresses. No DAD ever run -> duplicate address on-link. XXX acknowledged by code.

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Severity: Info
Status: new
Bucket: Base system — network stack
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U:C:N/I:L/A:L
CWE: CWE-20
File: sys/netinet6/in6.c
Lines: 1070-2453
Area: net
Discovered: 2026-06-30
Updated: 2026-06-30

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: likely
Tested: 2026-07-23 18:17:10
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 18:17:11
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-0343/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0343 · 1 files

File	Type	Description	Size
manifest.json	file		384 B	view raw

Fix verification

not_testable

baseline reproduced→ patch + rebuild →patched clean

recommended fix identified; fix.diff not authored/validated in this batch

recommended fix identified; fix.diff not authored/validated in this batch

combined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Info severity)

Evidence (decisive lines)

Source-confirmed at sys/netinet6/in6.c:1070: IPv6 addr configured while interface down bypasses DAD

Verified recommended fix

Source-confirmed at sys/netinet6/in6.c:1070: IPv6 addr configured while interface down bypasses DAD

Verdict

Source-confirmed at sys/netinet6/in6.c:1070: IPv6 addr configured while interface down bypasses DAD