CVE-2024-56740
CVE-2024-56740 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 7.8)
- EPSS exploit prediction: 0% (9th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2024-53383
- Weakness: CWE-787
- Affected product: Linux Linux Kernel
- Published:
- Last modified:
Description
In the Linux kernel, the following vulnerability has been resolved: nfs/localio: must clear res.replen in nfs_local_read_done Otherwise memory corruption can occur due to NFSv3 LOCALIO reads leaving garbage in res.replen: - nfs3_read_done() copies that into server->read_hdrsize; from there nfs3_proc_read_setup() copies it to args.replen in new requests. - nfs3_xdr_enc_read3args() passes that to rpc_prepare_reply_pages() which includes it in hdrsize for xdr_init_pages, so that rq_rcv_buf contains a ridiculous len. - This is copied to rq_private_buf and xs_read_stream_request() eventually passes the kvec to sock_recvmsg() which receives incoming data into entirely the wrong place. This is easily reproduced with NFSv3 LOCALIO that is servicing reads when it is made to pivot back to using normal RPC. This switch back to using normal NFSv3 with RPC can occur for a few reasons but this issue was exposed with a test that stops and then restarts the NFSv3 server while LOCALIO is performing heavy read IO.
Frequently asked questions
- What is CVE-2024-56740?
- In the Linux kernel, the following vulnerability has been resolved: nfs/localio: must clear res.replen in nfs_local_read_done Otherwise memory corruption can occur due to NFSv3 LOCALIO reads leaving garbage in res.replen: - nfs3_read_done() copies that into server->read_hdrsize; from there nfs3_proc_read_setup() copies it to args.replen in new requests. - nfs3_xdr_enc_read3args() passes that to rpc_prepare_reply_pages() which includes it in hdrsize for xdr_init_pages, so that rq_rcv_buf contains a ridiculous len. - This is copied to rq_private_buf and xs_read_stream_request() eventually passes the kvec to sock_recvmsg() which receives incoming data into entirely the wrong place. This is easily reproduced with NFSv3 LOCALIO that is servicing reads when it is made to pivot back to using normal RPC. This switch back to using normal NFSv3 with RPC can occur for a few reasons but this issue was exposed with a test that stops and then restarts the NFSv3 server while LOCALIO is performing heavy read IO.
- How severe is CVE-2024-56740?
- CVE-2024-56740 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2024-56740 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2024-56740?
- CVE-2024-56740 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2024-56740?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2024-56740 have an EU (EUVD) identifier?
- Yes. CVE-2024-56740 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-53383.
- When was CVE-2024-56740 published?
- CVE-2024-56740 was published on 2024-12-29 and last updated on 2026-06-17.
References
- https://git.kernel.org/stable/c/650703bc4ed3edf841e851c99ab8e7ba9e5262a3
- https://git.kernel.org/stable/c/de5dac261eeab99762bbdf7c20cee5d26ef4462e
Affected products (1)
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
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