Linux Kernel up to 7.1.9 macvlan macvlan_init use after free

CVSS Meta Temp Score
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CTI Interest Score
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9.5$5k-$25k0.30

Summaryinfo

A vulnerability identified as very critical has been detected in Linux Kernel up to 6.1.183/6.6.152/6.12.104/6.18.45/7.1.9. Affected by this issue is the function macvlan_init of the component macvlan. This manipulation causes use after free. This vulnerability appears as CVE-2026-74743. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.1.183/6.6.152/6.12.104/6.18.45/7.1.9. Affected by this vulnerability is the function macvlan_init of the component macvlan. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: macvlan: inherit needed_headroom and needed_tailroom from lowerdev macvlan devices inherit hard_header_len from lowerdev during macvlan_init(), but leave needed_headroom and needed_tailroom set to 0. When the underlying lowerdev requires extra headroom or tailroom for headers/trailers (e.g. macsec, ipsec, wireguard, tunnels, or veth with rx headroom), upper layers calculating packet headroom and tailroom fail to reserve sufficient space. This can result in reallocation overhead, skb headroom underflows, or KASAN slab-use-after-free crashes when dev_hard_header() / macvlan_hard_header() prepends header data or when lower devices append tailroom. Fix this by: 1. Inheriting needed_headroom and needed_tailroom from lowerdev in macvlan_init(). 2. Propagating needed_headroom and needed_tailroom updates to attached macvlans in macvlan_device_event() when receiving NETDEV_FEAT_CHANGE events.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-74743 since 08/15/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/26/2026).

Upgrading to version 6.1.184, 6.6.153, 6.12.105, 6.18.46 or 7.1.10 eliminates this vulnerability. Applying the patch 8cd90e850e434577bf6774778657d26d6995e53f/28afc87bd8da0b3348bbbd834c8a89e83712cf5e/8f6a05dbac05725e0786701eb04778c5bdbe4eaa/96fa90b74385b7f2b0d97251dd43d5ee6ca44668/bc9a00fb78e32bccc39d763bfd13a450705bac5d/cef51860becd9700217c81732ca1eb1ea6ed6fe1 is able to eliminate this problem.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.184/6.6.153/6.12.105/6.18.46/7.1.10
Patch: 8cd90e850e434577bf6774778657d26d6995e53f/28afc87bd8da0b3348bbbd834c8a89e83712cf5e/8f6a05dbac05725e0786701eb04778c5bdbe4eaa/96fa90b74385b7f2b0d97251dd43d5ee6ca44668/bc9a00fb78e32bccc39d763bfd13a450705bac5d/cef51860becd9700217c81732ca1eb1ea6ed6fe1

Timelineinfo

08/15/2026 CVE reserved
08/26/2026 +11 days Advisory disclosed
08/26/2026 +0 days VulDB entry created
08/26/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74743 (🔒)
GCVE (CVE): GCVE-0-2026-74743
GCVE (VulDB): GCVE-100-395803

Entryinfo

Created: 08/26/2026 17:03
Changes: 08/26/2026 17:03 (59)
Complete: 🔍
Cache ID: 216::103

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