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NVD / CVE Program· CNA Linux

CVE-2024-56779: nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.54% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0ab0a3ad24e970e894abcac58f85c332d1726749, 2d505a801e57428057563762f67a5a62009b2600, 37dfc81266d3a32294524bfadd3396614f8633ee; azl3 kernel 6.6.57.1-7 on Azure Linux 3.0 6.6.64.2-1; azl3 kernel 6.6.64.2-1 on Azure Linux 3.0 6.6.64.2-1.
  • Severity is disputed: the assigning authority (CNA) scores it 9.8, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 0ab0a3ad24e970e894abcac58f85c332d1726749, 2d505a801e57428057563762f67a5a62009b2600, 37dfc81266d3a32294524bfadd3396614f8633ee; azl3 kernel 6.6.57.1-7 on Azure Linux 3.0 6.6.64.2-1; azl3 kernel 6.6.64.2-1 on Azure Linux 3.0 6.6.64.2-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur The action force umount(umount -f) will attempt to kill all rpc_task even umount operation may ultimately fail if some files remain open. Consequently, if an action attempts to open a file, it can potentially send two rpc_task to nfs server. NFS CLIENT thread1 thread2 open("file") ... nfs4_do_open _nfs4_do_open _nfs4_open_and_get_state _nfs4_proc_open nfs4_run_open_task /* rpc_task1 */ rpc_run_task rpc_wait_for_completion_task umount -f nfs_umount_begin rpc_killall_tasks rpc_signal_task rpc_task1 been wakeup and return -512 _nfs4_do_open // while loop ... nfs4_run_open_task /* rpc_task2 */ rpc_run_task rpc_wait_for_completion_task While processing an open request, nfsd will first attempt to find or allocate an nfs4_openowner. If it finds an nfs4_openowner that is not marked as NFS4_OO_CONFIRMED, this nfs4_openowner will released. Since two rpc_task can attempt to open the same file simultaneously from the client to server, and because two instances of nfsd can run concurrently, this situation can lead to lots of memory leak. Additionally, when we echo 0 to /proc/fs/nfsd/threads, warning will be triggered. NFS SERVER nfsd1 nfsd2 echo 0 > /proc/fs/nfsd/threads nfsd4_open nfsd4_process_open1 find_or_alloc_open_stateowner // alloc oo1, stateid1 nfsd4_open nfsd4_process_open1 find_or_alloc_open_stateowner // find oo1, without NFS4_OO_CONFIRMED release_openowner unhash_openowner_locked list_del_init(&oo->oo_perclient) // cannot find this oo // from client, LEAK!!! alloc_stateowner // alloc oo2 nfsd4_process_open2 init_open_stateid // associate oo1 // with stateid1, stateid1 LEAK!!! nfs4_get_vfs_file // alloc nfsd_file1 and nfsd_file_mark1 // all LEAK!!! nfsd4_process_open2 ... write_threads ... nfsd_destroy_serv nfsd_shutdown_net nfs4_state_shutdown_net nfs4_state_destroy_net destroy_client __destroy_client // won't find oo1!!! nfsd_shutdown_generic nfsd_file_cache_shutdown kmem_cache_destroy for nfsd_file_slab and nfsd_file_mark_slab // bark since nfsd_file1 // and nfsd_file_mark1 // still alive ======================================================================= BUG nfsd_file (Not tainted): Objects remaining in nfsd_file on __kmem_cache_shutdown() ----------------------------------------------------------------------- Slab 0xffd4000004438a80 objects=34 used=1 fp=0xff11000110e2ad28 flags=0x17ffffc0000240(workingset|head|node=0|zone=2|lastcpupid=0x1fffff) CPU: 4 UID: 0 PID: 757 Comm: sh Not tainted 6.12.0-rc6+ #19 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dum ---truncated---

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jan 8, 2025
Updated
Oct 15, 2026
EPSS
0.5% · 45th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
9.8
4.3 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2024-56779

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernelbefore 5.4.287
  • linux linux kernel5.5 and later · before 5.10.231
  • linux linux kernel5.11 and later · before 5.15.174
  • linux linux kernel5.16 and later · before 6.1.120
  • linux linux kernel6.2 and later · before 6.6.64
  • linux linux kernel6.7 and later · before 6.12.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.17affected
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before a85364f0d30dee01c5d5b4afa55a9629a8f36d8eaffected · git
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before 2d505a801e57428057563762f67a5a62009b2600affected · git
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before 0ab0a3ad24e970e894abcac58f85c332d1726749affected · git
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before 45abb68c941ebc9a35c6d3a7b08196712093c636affected · git
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before 37dfc81266d3a32294524bfadd3396614f8633eeaffected · git
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before 6f73f920b7ad0084373e46121d7ac34117aed652affected · git
    • 3234975f477f746c22d076ea178a79ea104b2ca7 and later · before 98100e88dd8865999dc6379a3356cd799795fe7baffected · git
    • before 3.17not affected · semver
    • 5.4.287 and later · up to and including 5.4.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.123-16.1.123-1
Debian:13linuxbefore 6.12.5-16.12.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2024-56787Jan 8, 2025 · soc: imx8m: Probe the SoC driver as platform driver
    22Monitor
  • ← EarlierCVE-2024-56770Jan 8, 2025 · net/sched: netem: account for backlog updates from child qdisc
    22Monitor
  • Later →CVE-2024-56780Jan 8, 2025 · quota: flush quota_release_work upon quota writeback
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0ab0a3ad24e970e894abcac58f85c332d1726749Vendor (CNA)
Linux Linux2d505a801e57428057563762f67a5a62009b2600Vendor (CNA)
Linux Linux37dfc81266d3a32294524bfadd3396614f8633eeVendor (CNA)
Linux Linux45abb68c941ebc9a35c6d3a7b08196712093c636Vendor (CNA)
Linux Linux6f73f920b7ad0084373e46121d7ac34117aed652Vendor (CNA)
Linux Linux98100e88dd8865999dc6379a3356cd799795fe7bVendor (CNA)
Linux Linuxa85364f0d30dee01c5d5b4afa55a9629a8f36d8eVendor (CNA)
azl3 kernel 6.6.57.1-7 on Azure Linux 3.06.6.64.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.64.2-1 on Azure Linux 3.06.6.64.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.173.1-2 on CBL Mariner 2.05.15.176.3-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.173.1-2 on CBL-Mariner 2.05.15.176.3-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.176.3-1 on CBL Mariner 2.05.15.176.3-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.123-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-401 · Missing Release of Memory after Effective Lifetime

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (10 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records