# CVE-2026-89700

## Summary

- **CVE ID:** CVE-2026-89700
- **Severity:** UNKNOWN
- **CVSS Score:** 1.51
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 16, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

nfsd: validate sockaddr length per family in listener_set

nfsd_sock_nl_policy declares NFSD_A_SOCK_ADDR as a bare NLA_BINARY
attribute with no minimum length. A CAP_NET_ADMIN caller can send a
16-byte NFSD_A_SOCK_ADDR with sa_family=AF_INET6, causing a 12-byte
OOB read across three consumers (rpc_cmp_addr_port, svc_find_listener,
kernel_bind).

nfsd_nl_listener_set_doit() also parsed and validated each listener
entry inline in two separate loops, interleaved with mutating the
running listener configuration. The validation was duplicated, used an
open-coded "nla_len < sizeof(struct sockaddr)" check that was too short
for AF_INET6, and handled a malformed entry inconsistently depending on
which loop noticed it.

Add an nfsd_nl_validate_listeners() helper that walks the entire list
once and confirms each entry parses, carries both an address and a
transport name, and is long enough for its address family
(sizeof(struct sockaddr_in) for AF_INET, sizeof(struct sockaddr_in6)
for AF_INET6, -EAFNOSUPPORT otherwise). Call it before taking
nfsd_mutex or creating the serv, so a malformed request fails cleanly
with no side effects.

Since every entry is known valid by the time the two existing loops
run, drop the redundant presence and per-family length checks from
both, leaving only the nla_parse_nested() call needed to extract the
data.

## Affected Products

- Linux — Linux (16a471177496c8e04a9793812c187a2c1a2192fa)
- Linux — Linux (6.10)
- Linux — Linux (0)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/2aca70c18c5f5d06004122861fb151d5fcc57faf)
- [CNA](https://git.kernel.org/stable/c/22d0e4752ca88fd84196d22ebeedc905e6540440)
- [CNA](https://git.kernel.org/stable/c/bdcc85c2b05a9378d8bd2d65f9fc41440a3cf464)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._