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Fencer Vulns
high 7.8

CVE-2024-38626 json

fuse: clear FR_SENT when re-adding requests into pending list

published 2024-06-21 2 y ago modified 2026-08-05 3 mo ago also EUVD-2024-37489

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

fuse: clear FR_SENT when re-adding requests into pending list

The following warning was reported by lee bruce:

------------[ cut here ]------------ WARNING: CPU: 0 PID: 8264 at fs/fuse/dev.c:300 fuse_request_end+0x685/0x7e0 fs/fuse/dev.c:300 Modules linked in: CPU: 0 PID: 8264 Comm: ab2 Not tainted 6.9.0-rc7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:fuse_request_end+0x685/0x7e0 fs/fuse/dev.c:300 ...... Call Trace: <TASK> fuse_dev_do_read.constprop.0+0xd36/0x1dd0 fs/fuse/dev.c:1334 fuse_dev_read+0x166/0x200 fs/fuse/dev.c:1367 call_read_iter include/linux/fs.h:2104 [inline] new_sync_read fs/read_write.c:395 [inline] vfs_read+0x85b/0xba0 fs/read_write.c:476 ksys_read+0x12f/0x260 fs/read_write.c:619 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xce/0x260 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f ...... </TASK>

The warning is due to the FUSE_NOTIFY_RESEND notify sent by the write() syscall in the reproducer program and it happens as follows:

(1) calls fuse_dev_read() to read the INIT request The read succeeds. During the read, bit FR_SENT will be set on the request. (2) calls fuse_dev_write() to send an USE_NOTIFY_RESEND notify The resend notify will resend all processing requests, so the INIT request is moved from processing list to pending list again. (3) calls fuse_dev_read() with an invalid output address fuse_dev_read() will try to copy the same INIT request to the output address, but it will fail due to the invalid address, so the INIT request is ended and triggers the warning in fuse_request_end().

Fix it by clearing FR_SENT when re-adding requests into pending list.

Patch / fix

  • Linux Linux 6.9.4, 6.10

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-38626 updated cvss 5.5

kernel: fuse: clear FR_SENT when re-adding requests into pending list

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.