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NVD / CVE Program· CNA Linux

CVE-2024-49882: ext4: fix double brelse() the buffer of the extents path

Noroxi assessment

Priority: Monitor (action score 31/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.31% (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 230ee0535d01478bad9a3037292043f39b9be10b, 32bbb59e3f18facd7201bef110010bf35819b8c3, 68a69cf60660c73990c1875f94a5551600b04775; azl3 kernel 6.6.51.1-5 on Azure Linux 3.0 6.6.57.1-2; azl3 kernel 6.6.57.1-2 on Azure Linux 3.0 6.6.57.1-2.

Low priority for now. Upgrade to Linux Linux 230ee0535d01478bad9a3037292043f39b9be10b, 32bbb59e3f18facd7201bef110010bf35819b8c3, 68a69cf60660c73990c1875f94a5551600b04775; azl3 kernel 6.6.51.1-5 on Azure Linux 3.0 6.6.57.1-2; azl3 kernel 6.6.57.1-2 on Azure Linux 3.0 6.6.57.1-2 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: ext4: fix double brelse() the buffer of the extents path In ext4_ext_try_to_merge_up(), set path[1].p_bh to NULL after it has been released, otherwise it may be released twice. An example of what triggers this is as follows: split2 map split1 |--------|-------|--------| ext4_ext_map_blocks ext4_ext_handle_unwritten_extents ext4_split_convert_extents // path->p_depth == 0 ext4_split_extent // 1. do split1 ext4_split_extent_at |ext4_ext_insert_extent | ext4_ext_create_new_leaf | ext4_ext_grow_indepth | le16_add_cpu(&neh->eh_depth, 1) | ext4_find_extent | // return -ENOMEM |// get error and try zeroout |path = ext4_find_extent | path->p_depth = 1 |ext4_ext_try_to_merge | ext4_ext_try_to_merge_up | path->p_depth = 0 | brelse(path[1].p_bh) ---> not set to NULL here |// zeroout success // 2. update path ext4_find_extent // 3. do split2 ext4_split_extent_at ext4_ext_insert_extent ext4_ext_create_new_leaf ext4_ext_grow_indepth le16_add_cpu(&neh->eh_depth, 1) ext4_find_extent path[0].p_bh = NULL; path->p_depth = 1 read_extent_tree_block ---> return err // path[1].p_bh is still the old value ext4_free_ext_path ext4_ext_drop_refs // path->p_depth == 1 brelse(path[1].p_bh) ---> brelse a buffer twice Finally got the following WARRNING when removing the buffer from lru: ============================================ VFS: brelse: Trying to free free buffer WARNING: CPU: 2 PID: 72 at fs/buffer.c:1241 __brelse+0x58/0x90 CPU: 2 PID: 72 Comm: kworker/u19:1 Not tainted 6.9.0-dirty #716 RIP: 0010:__brelse+0x58/0x90 Call Trace: <TASK> __find_get_block+0x6e7/0x810 bdev_getblk+0x2b/0x480 __ext4_get_inode_loc+0x48a/0x1240 ext4_get_inode_loc+0xb2/0x150 ext4_reserve_inode_write+0xb7/0x230 __ext4_mark_inode_dirty+0x144/0x6a0 ext4_ext_insert_extent+0x9c8/0x3230 ext4_ext_map_blocks+0xf45/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] ============================================

HighCVSS 7.8 · v3.1—Proof of concept Fix available
Published
Oct 21, 2024
Updated
Aug 5, 2026
EPSS
0.3% · 25th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.8
CNA · Linux
7.8
agree

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
  • Proof of concept exists, no weaponized module
  • A fix has been released

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

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • 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
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • linux linux kernel3.7 and later · before 4.19.323
  • linux linux kernel4.20 and later · before 5.4.285
  • linux linux kernel5.5 and later · before 5.10.227
  • linux linux kernel5.11 and later · before 5.15.168
  • linux linux kernel5.16 and later · before 6.1.113
  • linux linux kernel6.2 and later · before 6.6.55
  • linux linux kernel6.7 and later · before 6.10.14
  • linux linux kernel6.11 and later · before 6.11.3

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

    • 3.7affected
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before d4574bda63906bf69660e001470bfe1a0ac524aeaffected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before f9fd47c9d9548f9e47fa60098eab99dde175401daffected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2eaffected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before 32bbb59e3f18facd7201bef110010bf35819b8c3affected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before 78bbc3d15b6f443acb26e94418c445bac940d414affected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before 68a69cf60660c73990c1875f94a5551600b04775affected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before 7633407ca4ab8be2916ab214eb44ccebc6a50e1aaffected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before 230ee0535d01478bad9a3037292043f39b9be10baffected · git
    • ecb94f5fdf4b72547fca022421a9dca1672bddd4 and later · before dcaa6c31134c0f515600111c38ed7750003e1b9caffected · git

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.115-16.1.115-1
Debian:13linuxbefore 6.11.4-16.11.4-1

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-2024-49879Oct 21, 2024 · drm: omapdrm: Add missing check for alloc_ordered_workqueue
    22Monitor
  • ← EarlierCVE-2024-49880Oct 21, 2024 · ext4: fix off by one issue in alloc_flex_gd()
    31Monitor
  • Later →CVE-2024-49883Oct 21, 2024 · ext4: aovid use-after-free in ext4_ext_insert_extent()
    31Monitor

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 Linux230ee0535d01478bad9a3037292043f39b9be10bVendor (CNA)
Linux Linux32bbb59e3f18facd7201bef110010bf35819b8c3Vendor (CNA)
Linux Linux68a69cf60660c73990c1875f94a5551600b04775Vendor (CNA)
Linux Linux7633407ca4ab8be2916ab214eb44ccebc6a50e1aVendor (CNA)
Linux Linux78bbc3d15b6f443acb26e94418c445bac940d414Vendor (CNA)
Linux Linuxb6c29c8f3d7cb67b505f3b2f6c242d52298d1f2eVendor (CNA)
Linux Linuxd4574bda63906bf69660e001470bfe1a0ac524aeVendor (CNA)
Linux Linuxdcaa6c31134c0f515600111c38ed7750003e1b9cVendor (CNA)
Linux Linuxf9fd47c9d9548f9e47fa60098eab99dde175401dVendor (CNA)
azl3 kernel 6.6.51.1-5 on Azure Linux 3.06.6.57.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.57.1-2 on Azure Linux 3.06.6.57.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.167.1-2 on CBL Mariner 2.05.15.173.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.167.1-2 on CBL-Mariner 2.05.15.173.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.173.1-1 on CBL Mariner 2.05.15.173.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.115-1 · Debian:12Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:122025-12-01

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.

  1. Published
  2. First PoC+405 d
  3. TodayNov 5, 2026+745 d

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.

  • CVE-2024-35814157 days apartswiotlb: Fix double-allocation of slots due to broken alignment handling
    35Monitor
  • CVE-2024-498530 days apartfirmware: arm_scmi: Fix double free in OPTEE transport
    31Monitor
  • CVE-2024-499830 days apartext4: drop ppath from ext4_ext_replay_update_ex() to avoid double-free
    31Monitor
  • CVE-2024-499890 days apartdrm/amd/display: fix double free issue during amdgpu module unload
    31Monitor
  • CVE-2024-500550 days apartdriver core: bus: Fix double free in driver API bus_register()
    31Monitor
  • CVE-2024-500717 days apartpinctrl: nuvoton: fix a double free in ma35_pinctrl_dt_node_to_map_func()
    31Monitor

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

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

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