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Vulnerability · Published May 27, 2026 · Assigned by Linux

CVE-2026-45889mptcp: do not account for OoO in mptcp_rcvbuf_grow()

Medium 5.5

In plain English

A medium-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.2%top 95.4% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: mptcp: do not account for OoO in mptcp_rcvbuf_grow() MPTCP-level OoOs are physiological when multiple subflows are active concurrently and will not cause retransmissions nor are caused by drops. Accounting for them in mptcp_rcvbuf_grow() causes the rcvbuf slowly drifting towards tcp_rmem[2]. Remove such accounting. Note that subflows will still account for TCP-level OoO when the MPTCP-level rcvbuf is propagated. This also closes a subtle and very unlikely race condition with rcvspace init; active sockets with user-space holding the msk-level socket lock, could complete such initialization in the receive callback, after that the first OoO data reaches the rcvbuf and potentially triggering a divide by zero Oops.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:14linux6.18.14-1DEBIAN-CVE-2026-45889
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-45889
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-45889

Affected products (as reported)

VendorProductVersions
Linux Linux e118cdc34dd109562b64f6a397f68cd33b041d5b – before fb7bf00b04a6b48859f52035d4e745848c2b4c79e118cdc34dd109562b64f6a397f68cd33b041d5b – before 400ee4854adef1e4983812a3decf6717ea020136e118cdc34dd109562b64f6a397f68cd33b041d5b – before 6b329393502e5857662b851a13f947209c588587
Linux Linux 6.18

References