In the Linux kernel, the following vulnerability has been resolved: nfsd: fix heap overflow in NFSv4.0 LOCK replay cache The NFSv4.0 replay cache uses a fixed 112-byte inline buffer (rp_ibuf[NFSD4_REPLAY_ISIZE]) to store encoded operation responses. This size was calculated based on OPEN responses and does not account for LOCK denied responses, which include the conflicting lock owner as a variable-length field up to 1024 bytes (NFS4_OPAQUE_LIMIT). When a LOCK operation is denied due to a conflict with an existing lock that has a large owner, nfsd4_encode_operation() copies the full encoded response into the undersized replay buffer via read_bytes_from_xdr_buf() with no bounds check. This results in a slab-out-of-bounds write of up to 944 bytes past the end of the buffer, corrupting adjacent heap memory. This can be triggered remotely by an unauthenticated attacker with two cooperating NFSv4.0 clients: one sets a lock with a large owner string, then the other requests a conflicting lock to provoke the denial. We could fix this by increasing NFSD4_REPLAY_ISIZE to allow for a full opaque, but that would increase the size of every stateowner, when most lockowners are not that large. Instead, fix this by checking the encoded response length against NFSD4_REPLAY_ISIZE before copying into the replay buffer. If the response is too large, set rp_buflen to 0 to skip caching the replay payload. The status is still cached, and the client already received the correct response on the original request.

redhat RHSA-2026:11313: RHSA-2026:11313: kernel security update (Moderate)

An update of the linux package has been released.

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:10108 advisory.

    The kernel packages contain the Linux kernel, the core of any Linux operating system.

    Security Fix(es):

    * kernel: Bluetooth: MGMT: Fix possible UAFs (CVE-2025-39981)

    * kernel: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats (CVE-2025-68800)

    * kernel: Linux kernel: Denial of Service due to a deadlock in hugetlb folio migration (CVE-2026-23097)

    * kernel: Linux kernel: Denial of Service via unsafe requeue in rxrpc_recvmsg (CVE-2026-23066)

    * kernel: Kernel: Privilege escalation or denial of service in nf_tables via inverted element activity     check (CVE-2026-23111)

    * kernel: Linux kernel: Local denial of service and memory leak in DAMON sysfs via setup failure     (CVE-2026-23144)

    * kernel: Linux kernel: Use-after-free in bonding module can cause system crash or arbitrary code     execution (CVE-2026-23171)

    * kernel: scsi: target: iscsi: Fix use-after-free in iscsit_dec_session_usage_count() (CVE-2026-23193)

    * kernel: net/sched: cls_u32: use skb_header_pointer_careful() (CVE-2026-23204)

    * kernel: kernel: Privilege escalation or denial of service via use-after-free in nf_tables_addchain()     (CVE-2026-23231)

    * kernel: nfsd: fix heap overflow in NFSv4.0 LOCK replay cache (CVE-2026-31402)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - nfsd: fix heap overflow in NFSv4.0 LOCK replay cache The NFSv4.0 replay cache uses a fixed 112-byte inline     buffer (rp_ibuf[NFSD4_REPLAY_ISIZE]) to store encoded operation responses. This size was calculated based     on OPEN responses and does not account for LOCK denied responses, which include the conflicting lock owner     as a variable-length field up to 1024 bytes (NFS4_OPAQUE_LIMIT). When a LOCK operation is denied due to a     conflict with an existing lock that has a large owner, nfsd4_encode_operation() copies the full encoded     response into the undersized replay buffer via read_bytes_from_xdr_buf() with no bounds check. This     results in a slab-out-of-bounds write of up to 944 bytes past the end of the buffer, corrupting adjacent     heap memory. This can be triggered remotely by an unauthenticated attacker with two cooperating NFSv4.0     clients: one sets a lock with a large owner string, then the other requests a conflicting lock to provoke     the denial. We could fix this by increasing NFSD4_REPLAY_ISIZE to allow for a full opaque, but that would     increase the size of every stateowner, when most lockowners are not that large. Instead, fix this by     checking the encoded response length against NFSD4_REPLAY_ISIZE before copying into the replay buffer. If     the response is too large, set rp_buflen to 0 to skip caching the replay payload. The status is still     cached, and the client already received the correct response on the original request. (CVE-2026-31402)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
310098	Photon OS 4.0: Linux PHSA-2026-4.0-1002	Nessus	PhotonOS Local Security Checks	high
310035	RHEL 9 : kernel (RHSA-2026:10108)	Nessus	Red Hat Local Security Checks	high
306005	Photon OS 5.0: Linux PHSA-2026-5.0-0813	Nessus	PhotonOS Local Security Checks	high
304931	Linux Distros Unpatched Vulnerability : CVE-2026-31402	Nessus	Misc.	high

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