Security readout for executives and security teams
Plain-English summary
A Linux NFS client flaw can corrupt memory during NFSv3 LOCALIO reads when processing switches back to normal RPC. Successful triggering could compromise confidentiality, integrity, and availability. Exposure appears limited to specific kernel versions and configurations, so organizations should prioritize systems actively using NFSv3 LOCALIO.
Executive priority
Treat this as high priority for systems using NFSv3 LOCALIO because memory corruption may affect confidentiality, integrity, and availability. Prioritize configuration discovery and vendor-supported updates. Systems not using this feature have substantially lower apparent exposure, although exact affected-version boundaries should be confirmed with their Linux distributor.
Technical view
An uncleared res.replen value can propagate through NFSv3 read setup into RPC reply-page sizing. The resulting invalid receive-buffer length can cause incoming network data to be written to the wrong memory location. The issue is classified as CWE-787 with CVSS 3.1 score 7.8.
Likely exposure
Potentially affected Linux 6.12 and 6.13 systems using NFSv3 LOCALIO are the primary concern. The supplied version data is ambiguous around exact fixed releases. The documented trigger involves active reads followed by fallback to normal NFSv3 RPC, including after stopping and restarting the NFS server.
Exploitation context
The CVSS vector describes local access, low complexity, low privileges, and no user interaction. The source reports easy reproduction under a specific NFS workload, but provides no evidence of active exploitation. CVE-2024-56740 is not identified as a CISA KEV entry in the supplied bundle.
Researcher notes
The vulnerable data flow crosses nfs3_read_done(), nfs3_proc_read_setup(), nfs3_xdr_enc_read3args(), rpc_prepare_reply_pages(), xdr_init_pages(), and xs_read_stream_request(). The supplied stable commits are the authoritative remediation references. Public evidence does not establish weaponization, active exploitation, or a broader remotely reachable attack path.
Mitigation direction
- Inventory Linux systems using NFSv3 LOCALIO, focusing on reported 6.12 and 6.13 versions.
- Apply a vendor-supported kernel update containing the referenced stable fix.
- Check distribution or kernel-vendor guidance for exact fixed package versions and interim mitigations.
- Prioritize systems where NFS services restart or LOCALIO frequently falls back to RPC.
Validation and detection
- Record each system's running kernel version and compare it with vendor-fixed package guidance.
- Confirm whether NFSv3 LOCALIO is enabled and actively serving reads.
- Verify the deployed kernel includes the referenced res.replen-clearing change.
- Test LOCALIO reads and RPC fallback after remediation in a controlled environment.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2024-56740 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/de5dac261eeab99762bbdf7c20cee5d26ef4462eCVE reference, Linux
- https://git.kernel.org/stable/c/650703bc4ed3edf841e851c99ab8e7ba9e5262a3CVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.