CVE-2026-74666

packet: synchronize pressure clearing with ring reconfiguration

Published Aug 22, 2026 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Description

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

packet: synchronize pressure clearing with ring reconfiguration

packet_set_ring() updates the RX ring state under sk_receive_queue.lock,
but used to publish the tpacket receive mode through po->prot_hook.func
after releasing that lock. packet_poll() and packet_recvmsg() can then
run the pressure clearing path after the ring has been cleared while
still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference
stale or NULL ring storage.

Move the existing receive hook assignment into the same
sk_receive_queue.lock section as the ring state update. Keep the
assignment otherwise unchanged, including on TX ring reconfiguration, to
avoid adding behavior changes that are not required for the fix.

Serialize packet_recvmsg() pressure clearing with the same queue lock
only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear
and the socket has moved away from tpacket_rcv, packet_set_ring() has
already detached the socket and waited for synchronize_net(), so no new
packet input can set the flag again.

packet_poll() already holds sk_receive_queue.lock, so it uses the new
unlocked helper directly.

Analysis

Technical impact

The vulnerability is a race condition in the Linux kernel's packet socket implementation that can lead to a use‑after‑free followed by a null‑pointer dereference, resulting in a kernel panic and loss of service.

Affected Systems

All Linux kernels that expose AF_PACKET sockets and have not yet incorporated the listed security commits (1a35da325cac4d5bcad76a2aa943408a6f1d9000, 2c7b5eb87b2b288cdbde825f21d2b83b2f5da747, a08196c3cc105947746ec21309edfbb60275fcdb, ad740b4990347521f0db260d381f9f74e7b340ba, cf8189b82bb93f219ab740e0346c919ad65ada62) are affected. The advisory does not specify a version range; any kernel containing these commit hashes is considered fixed.

Risk and Exploitability

Exploitation requires local control over a packet socket, which normally requires root or CAP_NET_ADMIN; thus the likely attack vector is a local privileged attacker. The CVSS score of 7.8 indicates high severity, while the EPSS score of < 1% signals a low probability of exploitation in the wild. The vulnerability is not present in the CISA KEV catalog. Triggering the race condition will crash the kernel, causing a denial of service.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< bf3c8e86bc8ad111be3f3136125e255344bcb3da
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< 8cfb2e71926a682f36c4240067d424074dd8f70f
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< f015c9de92b731814059a343b765c60c0196225c
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< cf8189b82bb93f219ab740e0346c919ad65ada62
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< ad740b4990347521f0db260d381f9f74e7b340ba
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< 2c7b5eb87b2b288cdbde825f21d2b83b2f5da747
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< a08196c3cc105947746ec21309edfbb60275fcdb
`2ccdbaa6d55b0656244ba57c4b56765a0af76c0a`	affected	< 1a35da325cac4d5bcad76a2aa943408a6f1d9000

Linux

affected

Version	Status	Constraints
`4.2`	affected	—
`0`	unaffected	< 4.2
`5.10.267`	unaffected	≤ 5.10.*
`5.15.218`	unaffected	≤ 5.15.*
`6.1.185`	unaffected	≤ 6.1.*
`6.6.152`	unaffected	≤ 6.6.*
`6.12.104`	unaffected	≤ 6.12.*
`6.18.45`	unaffected	≤ 6.18.*
`7.1.9`	unaffected	≤ 7.1.*
`7.2`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[2ccdbaa6d55b0656244ba57c4b56765a0af76c0a,cf8189b82bb93f219ab740e0346c919ad65ada62)`	affected	code_commit	—
`[2ccdbaa6d55b0656244ba57c4b56765a0af76c0a,ad740b4990347521f0db260d381f9f74e7b340ba)`	affected	code_commit	—
`[2ccdbaa6d55b0656244ba57c4b56765a0af76c0a,2c7b5eb87b2b288cdbde825f21d2b83b2f5da747)`	affected	code_commit	—
`[2ccdbaa6d55b0656244ba57c4b56765a0af76c0a,a08196c3cc105947746ec21309edfbb60275fcdb)`	affected	code_commit	—
`[2ccdbaa6d55b0656244ba57c4b56765a0af76c0a,1a35da325cac4d5bcad76a2aa943408a6f1d9000)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`4.2`	affected	generic	—
`[0,4.2)`	unaffected	semver	—
`[6.6.152,6.7.0)`	unaffected	semver	—
`[6.12.104,6.13.0)`	unaffected	semver	—
`[6.18.45,6.19.0)`	unaffected	semver	—
`[7.1.9,7.2.0)`	unaffected	semver	—
`[7.2,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the kernel to a version that contains the commit hashes listed in the advisory, which implement the packet_set_ring and packet_recvmsg fixes.
If an upgrade cannot be performed immediately, disable or restrict AF_PACKET socket creation for unprivileged users by setting appropriate sysctl limits or compiling the kernel with CONFIG_PACKET disabled.
Monitor system logs for kernel panic or abnormal packet socket activity and apply the patch as soon as a compatible kernel release becomes available.

Generated by OpenCVE AI on August 25, 2026 at 07:44 UTC.

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4777-1	linux security update
Debian DLA	DLA-4788-1	linux-6.12 security update
Debian DSA	DSA-6466-1	linux security update
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.129% probability within 30 days)

Exploitation none

Automatable no

Technical Impact total

References

Link	Providers
https://git.kernel.org/stable/c/1a35da325cac4d5bcad76a2aa943408a6f1d9000
https://git.kernel.org/stable/c/2c7b5eb87b2b288cdbde825f21d2b83b2f5da747
https://git.kernel.org/stable/c/8cfb2e71926a682f36c4240067d424074dd8f70f
https://git.kernel.org/stable/c/a08196c3cc105947746ec21309edfbb60275fcdb
https://git.kernel.org/stable/c/ad740b4990347521f0db260d381f9f74e7b340ba
https://git.kernel.org/stable/c/bf3c8e86bc8ad111be3f3136125e255344bcb3da
https://git.kernel.org/stable/c/cf8189b82bb93f219ab740e0346c919ad65ada62
https://git.kernel.org/stable/c/f015c9de92b731814059a343b765c60c0196225c
https://lore.kernel.org/linux-cve-announce/2026082228-CVE-2026-74666-f951@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-74666
https://www.cve.org/CVERecord?id=CVE-2026-74666

History

Oct 16, 2026 8:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Aug 27, 2026 1:00 PM Added references View changes

Type	Values Removed	Values Added
References		https://git.kernel.org/stable/c/8cfb2e71926a682f36c4240067d424074dd8f70f https://git.kernel.org/stable/c/bf3c8e86bc8ad111be3f3136125e255344bcb3da https://git.kernel.org/stable/c/f015c9de92b731814059a343b765c60c0196225c

Aug 25, 2026 6:00 AM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}`	cvssV3_1 `{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Aug 24, 2026 2:30 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses	CWE-362 CWE-416

Aug 24, 2026 12:15 PM Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
References		https://lore.kernel.org/linux-cve-announce/2026082228-CVE-2026-74666-f951@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-74666 https://www.cve.org/CVERecord?id=CVE-2026-74666
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Moderate`

Aug 22, 2026 7:30 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-362 CWE-416 CWE-476

Aug 22, 2026 3:45 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: packet: synchronize pressure clearing with ring reconfiguration packet_set_ring() updates the RX ring state under sk_receive_queue.lock, but used to publish the tpacket receive mode through po->prot_hook.func after releasing that lock. packet_poll() and packet_recvmsg() can then run the pressure clearing path after the ring has been cleared while still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference stale or NULL ring storage. Move the existing receive hook assignment into the same sk_receive_queue.lock section as the ring state update. Keep the assignment otherwise unchanged, including on TX ring reconfiguration, to avoid adding behavior changes that are not required for the fix. Serialize packet_recvmsg() pressure clearing with the same queue lock only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear and the socket has moved away from tpacket_rcv, packet_set_ring() has already detached the socket and waited for synchronize_net(), so no new packet input can set the flag again. packet_poll() already holds sk_receive_queue.lock, so it uses the new unlocked helper directly.
Title		packet: synchronize pressure clearing with ring reconfiguration
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/1a35da325cac4d5bcad76a2aa943408a6f1d9000 https://git.kernel.org/stable/c/2c7b5eb87b2b288cdbde825f21d2b83b2f5da747 https://git.kernel.org/stable/c/a08196c3cc105947746ec21309edfbb60275fcdb https://git.kernel.org/stable/c/ad740b4990347521f0db260d381f9f74e7b340ba https://git.kernel.org/stable/c/cf8189b82bb93f219ab740e0346c919ad65ada62