What’s Vulnerable › Vulnerabilities

CVE-2021-47001: xprtrdma: Fix cwnd update ordering

• Severity: medium (CVSS 4.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-02-28 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: xprtrdma: Fix cwnd update ordering After a reconnect, the reply handler is opening the cwnd (and thus enabling more RPC Calls to be sent) /before/ rpcrdma_post_recvs() can post enough Receive WRs to receive their replies. This causes an RNR and the new connection is lost immediately. The race is most clearly exposed when KASAN and disconnect injection are enabled. This slows down rpcrdma_rep_create() enough to allow the send side to post a bunch of RPC Calls before the Receive completion handler can invoke ib_post_recv().

Affected products

• Linux kernel: from 5.5 before 5.10.38; from 5.11 before 5.11.22; from 5.12 before 5.12.5 — fixed in 5.10.38, 5.11.22, 5.12.5

How to fix

Upgrade to a fixed version: Linux kernel 5.10.38, 5.11.22, 5.12.5. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/19b5fa9489b5706bc878c3a522a7f771079e2fa0
• https://git.kernel.org/stable/c/35d8b10a25884050bb3b0149b62c3818ec59f77c
• https://git.kernel.org/stable/c/8834ecb5df22b7ff3c9b0deba7726579bb613f95
• https://git.kernel.org/stable/c/eddae8be7944096419c2ae29477a45f767d0fcd4
• https://git.kernel.org/stable/c/19b5fa9489b5706bc878c3a522a7f771079e2fa0
• https://git.kernel.org/stable/c/35d8b10a25884050bb3b0149b62c3818ec59f77c
• https://git.kernel.org/stable/c/8834ecb5df22b7ff3c9b0deba7726579bb613f95
• https://git.kernel.org/stable/c/eddae8be7944096419c2ae29477a45f767d0fcd4
• https://security.netapp.com/advisory/ntap-20250411-0001/

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