Evidence used
- No CISA KEV confirmation is currently recorded.
- Exploitation requires an existing local or physical foothold with privileges.
- EPSS is 0.21% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2024
CVE-2024-38636High confidence
f2fs: multidev: fix to recognize valid zero block address
Linux · Linux
5.5MediumCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 13 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Low, lowered one band.downgradedsince 11 May 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Linux Linux and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 13 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Canonical Ubuntu Security: 13 affected package states with no published fix
Distribution package intelligence
17 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 13 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.1.94-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-aws | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-gcp | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-gke | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-ibm | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-lowlatency | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-nvidia | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-nvidia-lowlatency | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-oem-6.8 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-oracle | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-raspi | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-riscv | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 13 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
In the Linux kernel, the following vulnerability has been resolved: f2fs: multidev: fix to recognize valid zero block address As reported by Yi Zhang in mailing list [1], kernel warning was catched during zbd/010 test as below: ./check zbd/010 zbd/010 (test gap zone support with F2FS) [failed] runtime ... 3.752s something found in dmesg: [ 4378.146781] run blktests zbd/010 at 2024-02-18 11:31:13 [ 4378.192349] null_blk: module loaded [ 4378.209860] null_blk: disk nullb0 created [ 4378.413285] scsi_debug:sdebug_driver_probe: scsi_debug: trim poll_queues to 0. poll_q/nr_hw = (0/1) [ 4378.422334] scsi host15: scsi_debug: version 0191 [20210520] dev_size_mb=1024, opts=0x0, submit_queues=1, statistics=0 [ 4378.434922] scsi 15:0:0:0: Direct-Access-ZBC Linux scsi_debug 0191 PQ: 0 ANSI: 7 [ 4378.443343] scsi 15:0:0:0: Power-on or device reset occurred [ 4378.449371] sd 15:0:0:0: Attached scsi generic sg5 type 20 [ 4378.449418] sd 15:0:0:0: [sdf] Host-managed zoned block device ... (See '/mnt/tests/gitlab.com/api/v4/projects/19168116/repository/archive.zip/storage/blktests/blk/blktests/results/nodev/zbd/010.dmesg' WARNING: CPU: 22 PID: 44011 at fs/iomap/iter.c:51 CPU: 22 PID: 44011 Comm: fio Not tainted 6.8.0-rc3+ #1 RIP: 0010:iomap_iter+0x32b/0x350 Call Trace: <TASK> __iomap_dio_rw+0x1df/0x830 f2fs_file_read_iter+0x156/0x3d0 [f2fs] aio_read+0x138/0x210 io_submit_one+0x188/0x8c0 __x64_sys_io_submit+0x8c/0x1a0 do_syscall_64+0x86/0x170 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Shinichiro Kawasaki helps to analyse this issue and proposes a potential fixing patch in [2]. Quoted from reply of Shinichiro Kawasaki: "I confirmed that the trigger commit is dbf8e63f48af as Yi reported. I took a look in the commit, but it looks fine to me. So I thought the cause is not in the commit diff. I found the WARN is printed when the f2fs is set up with multiple devices, and read requests are mapped to the very first block of the second device in the direct read path. In this case, f2fs_map_blocks() and f2fs_map_blocks_cached() modify map->m_pblk as the physical block address from each block device. It becomes zero when it is mapped to the first block of the device. However, f2fs_iomap_begin() assumes that map->m_pblk is the physical block address of the whole f2fs, across the all block devices. It compares map->m_pblk against NULL_ADDR == 0, then go into the unexpected branch and sets the invalid iomap->length. The WARN catches the invalid iomap->length. This WARN is printed even for non-zoned block devices, by following steps. - Create two (non-zoned) null_blk devices memory backed with 128MB size each: nullb0 and nullb1. # mkfs.f2fs /dev/nullb0 -c /dev/nullb1 # mount -t f2fs /dev/nullb0 "${mount_dir}" # dd if=/dev/zero of="${mount_dir}/test.dat" bs=1M count=192 # dd if="${mount_dir}/test.dat" of=/dev/null bs=1M count=192 iflag=direct ..." So, the root cause of this issue is: when multi-devices feature is on, f2fs_map_blocks() may return zero blkaddr in non-primary device, which is a verified valid block address, however, f2fs_iomap_begin() treats it as an invalid block address, and then it triggers the warning in iomap framework code. Finally, as discussed, we decide to use a more simple and direct way that checking (map.m_flags & F2FS_MAP_MAPPED) condition instead of (map.m_pblk != NULL_ADDR) to fix this issue. Thanks a lot for the effort of Yi Zhang and Shinichiro Kawasaki on this issue. [1] https://lore.kernel.org/linux-f2fs-devel/CAHj4cs-kfojYC9i0G73PRkYzcxCTex=-vugRFeP40g_URGvnfQ@mail.gmail.com/ [2] https://lore.kernel.org/linux-f2fs-devel/gngdj77k4picagsfdtiaa7gpgnup6fsgwzsltx6milmhegmjff@iax2n4wvrqye/
What
In the Linux kernel, the following vulnerability has been resolved: f2fs: multidev: fix to recognize valid zero block address As reported by Yi Zhang in mailing list [1], kernel warning was catched during zbd/010 test as below: ./check zbd/010 zbd/010 (test gap zone support with F2FS) [failed] runtime ... 3.752s something found in dmesg: [ 4378.146781] run blktests zbd/010 at 2024-02-18 11:31:13 [ 4378.192349] null_blk: module loaded [ 4378.209860] null_blk: disk nullb0 created [ 4378.413285] scsi_debug:sdebug_driver_probe: scsi_debug: trim poll_queues to 0. poll_q/nr_hw = (0/1) [ 4378.422334] scsi host15: scsi_debug: version 0191 [20210520] dev_size_mb=1024, opts=0x0, submit_queues=1, statistics=0 [ 4378.434922] scsi 15:0:0:0: Direct-Access-ZBC Linux scsi_debug 0191 PQ: 0 ANSI: 7 [ 4378.443343] scsi 15:0:0:0: Power-on or device reset occurred [ 4378.449371] sd 15:0:0:0: Attached scsi generic sg5 type 20 [ 4378.449418] sd 15:0:0:0: [sdf] Host-managed zoned block device ... (See '/mnt/tests/gitlab.com/api/v4/projects/19168116/repository/archive.zip/storage/blktests/blk/blktests/results/nodev/zbd/010.dmesg' WARNING: CPU: 22 PID: 44011 at fs/iomap/iter.c:51 CPU: 22 PID: 44011 Comm: fio Not tainted 6.8.0-rc3+ #1 RIP: 0010:iomap_iter+0x32b/0x350 Call Trace: <TASK> __iomap_dio_rw+0x1df/0x830 f2fs_file_read_iter+0x156/0x3d0 [f2fs] aio_read+0x138/0x210 io_submit_one+0x188/0x8c0 __x64_sys_io_submit+0x8c/0x1a0 do_syscall_64+0x86/0x170 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Shinichiro Kawasaki helps to analyse this issue and proposes a potential fixing patch in [2]. Quoted from reply of Shinichiro Kawasaki: "I confirmed that the trigger commit is dbf8e63f48af as Yi reported. I took a look in the commit, but it looks fine to me. So I thought the cause is not in the commit diff. I found the WARN is printed when the f2fs is set up with multiple devices, and read requests are mapped to the very first block of the second device in the direct read path. In this case, f2fs_map_blocks() and f2fs_map_blocks_cached() modify map->m_pblk as the physical block address from each block device. It becomes zero when it is mapped to the first block of the device. However, f2fs_iomap_begin() assumes that map->m_pblk is the physical block address of the whole f2fs, across the all block devices. It compares map->m_pblk against NULL_ADDR == 0, then go into the unexpected branch and sets the invalid iomap->length. The WARN catches the invalid iomap->length. This WARN is printed even for non-zoned block devices, by following steps. - Create two (non-zoned) null_blk devices memory backed with 128MB size each: nullb0 and nullb1. # mkfs.f2fs /dev/nullb0 -c /dev/nullb1 # mount -t f2fs /dev/nullb0 "${mount_dir}" # dd if=/dev/zero of="${mount_dir}/test.dat" bs=1M count=192 # dd if="${mount_dir}/test.dat" of=/dev/null bs=1M count=192 iflag=direct ..." So, the root cause of this issue is: when multi-devices feature is on, f2fs_map_blocks() may return zero blkaddr in non-primary device, which is a verified valid block address, however, f2fs_iomap_begin() treats it as an invalid block address, and then it triggers the warning in iomap framework code. Finally, as discussed, we decide to use a more simple and direct way that checking (map.m_flags & F2FS_MAP_MAPPED) condition instead of (map.m_pblk != NULL_ADDR) to fix this issue. Thanks a lot for the effort of Yi Zhang and Shinichiro Kawasaki on this issue. [1] https://lore.kernel.org/linux-f2fs-devel/CAHj4cs-kfojYC9i0G73PRkYzcxCTex=-vugRFeP40g_URGvnfQ@mail.gmail.com/ [2] https://lore.kernel.org/linux-f2fs-devel/gngdj77k4picagsfdtiaa7gpgnup6fsgwzsltx6milmhegmjff@iax2n4wvrqye/
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
In the Linux kernel, the following vulnerability has been resolved: f2fs: multidev: fix to recognize valid zero block address As reported by Yi Zhang in mailing list [1], kernel warning was catched during zbd/010 test as below: ./check zbd/010 zbd/010 (test gap zone support with F2FS) [failed] runtime ... 3.752s something found in dmesg: [ 4378.146781] run blktests zbd/010 at 2024-02-18 11:31:13 [ 4378.192349] null_blk: module loaded [ 4378.209860] null_blk: disk nullb0 created [ 4378.413285] scsi_debug:sdebug_driver_probe: scsi_debug: trim poll_queues to 0. poll_q/nr_hw = (0/1) [ 4378.422334] scsi host15: scsi_debug: version 0191 [20210520] dev_size_mb=1024, opts=0x0, submit_queues=1, statistics=0 [ 4378.434922] scsi 15:0:0:0: Direct-Access-ZBC Linux scsi_debug 0191 PQ: 0 ANSI: 7 [ 4378.443343] scsi 15:0:0:0: Power-on or device reset occurred [ 4378.449371] sd 15:0:0:0: Attached scsi generic sg5 type 20 [ 4378.449418] sd 15:0:0:0: [sdf] Host-managed zoned block device ... (See '/mnt/tests/gitlab.com/api/v4/projects/19168116/repository/archive.zip/storage/blktests/blk/blktests/results/nodev/zbd/010.dmesg' WARNING: CPU: 22 PID: 44011 at fs/iomap/iter.c:51 CPU: 22 PID: 44011 Comm: fio Not tainted 6.8.0-rc3+ #1 RIP: 0010:iomap_iter+0x32b/0x350 Call Trace: <TASK> __iomap_dio_rw+0x1df/0x830 f2fs_file_read_iter+0x156/0x3d0 [f2fs] aio_read+0x138/0x210 io_submit_one+0x188/0x8c0 __x64_sys_io_submit+0x8c/0x1a0 do_syscall_64+0x86/0x170 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Shinichiro Kawasaki helps to analyse this issue and proposes a potential fixing patch in [2]. Quoted from reply of Shinichiro Kawasaki: "I confirmed that the trigger commit is dbf8e63f48af as Yi reported. I took a look in the commit, but it looks fine to me. So I thought the cause is not in the commit diff. I found the WARN is printed when the f2fs is set up with multiple devices, and read requests are mapped to the very first block of the second device in the direct read path. In this case, f2fs_map_blocks() and f2fs_map_blocks_cached() modify map->m_pblk as the physical block address from each block device. It becomes zero when it is mapped to the first block of the device. However, f2fs_iomap_begin() assumes that map->m_pblk is the physical block address of the whole f2fs, across the all block devices. It compares map->m_pblk against NULL_ADDR == 0, then go into the unexpected branch and sets the invalid iomap->length. The WARN catches the invalid iomap->length. This WARN is printed even for non-zoned block devices, by following steps. - Create two (non-zoned) null_blk devices memory backed with 128MB size each: nullb0 and nullb1. # mkfs.f2fs /dev/nullb0 -c /dev/nullb1 # mount -t f2fs /dev/nullb0 "${mount_dir}" # dd if=/dev/zero of="${mount_dir}/test.dat" bs=1M count=192 # dd if="${mount_dir}/test.dat" of=/dev/null bs=1M count=192 iflag=direct ..." So, the root cause of this issue is: when multi-devices feature is on, f2fs_map_blocks() may return zero blkaddr in non-primary device, which is a verified valid block address, however, f2fs_iomap_begin() treats it as an invalid block address, and then it triggers the warning in iomap framework code. Finally, as discussed, we decide to use a more simple and direct way that checking (map.m_flags & F2FS_MAP_MAPPED) condition instead of (map.m_pblk != NULL_ADDR) to fix this issue. Thanks a lot for the effort of Yi Zhang and Shinichiro Kawasaki on this issue. [1] https://lore.kernel.org/linux-f2fs-devel/CAHj4cs-kfojYC9i0G73PRkYzcxCTex=-vugRFeP40g_URGvnfQ@mail.gmail.com/ [2] https://lore.kernel.org/linux-f2fs-devel/gngdj77k4picagsfdtiaa7gpgnup6fsgwzsltx6milmhegmjff@iax2n4wvrqye/
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- local access → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration. - CWE not yet assigned
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 21 Jun 2024 · Last source change 11 May 2026, 20:20 UTC · CWE not yet assigned
CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2024-37499
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD enriched
Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.