CVE-2026-57842: NetBSD COMPAT_NETBSD32 Double Free / Use-After-Free via recvmsg() msg_iovlen

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-11 · updated 2026-09-24
Weakness: CWE-415

Description

NetBSD contains a use-after-free and double-free vulnerability in msg_recv_copyin() within the COMPAT_NETBSD32 compatibility layer due to a missing return statement before the cleanup label on the success path. Any local user able to execute a 32-bit binary on a 64-bit NetBSD system can trigger a kernel panic or memory corruption by calling recvmsg() with msg_iovlen between 9 and IOV_MAX, causing the kernel to access a freed iovec buffer and subsequently free the same allocation a second time.

Affected products

The NetBSD Foundation NetBSD: from 8.0 through 8.3; from 9.0 before 9.5; from 10.0 through 10.1 — fixed in 9.5

How to fix

Upgrade to a fixed version: The NetBSD Foundation NetBSD 9.5. Check the vendor advisory for mitigations.

References

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