SB2026060615 - Ubuntu update for linux
Published: June 6, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 6 vulnerabilities.
1) Resource management error (CVE-ID: CVE-2026-43284)
CWE-ID: CWE-399 - Resource Management Errors
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/U:Amber
The vulnerability allows a local user to escalate privileges on the system.
The xfrm-ESP Page-Cache Write vulnerability exists due to improper management of internal resources in esp_input() function in net/ipv4/esp4.c and esp6_input() function in net/ipv6/esp6.c. A local user can execute arbitrary code with root privileges.
Note, this is one of two vulnerabilities reported as Dirty Frag.
2) Resource management error (CVE-ID: CVE-2026-43500)
CWE-ID: CWE-399 - Resource Management Errors
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/U:Amber
The vulnerability allows a local user to escalate privileges on the system.
The RxRPC Page-Cache Write vulnerability exists due to improper management of internal resources. A local user can execute arbitrary code with root privileges.
Note, this vulnerability is one of two issues described as Dirty Frag.
3) Improper control of a resource through its lifetime (CVE-ID: CVE-2026-43503)
CWE-ID: CWE-664 - Improper control of a resource through its lifetime
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to modify the page cache of a root-owned read-only file.
The vulnerability exists due to improper state management in frag-transfer helpers in the Linux kernel networking stack when moving fragment descriptors between socket buffers. A local user can trigger packet processing through a duplicated skb path to modify the page cache of a root-owned read-only file.
One demonstrated path involves ESP input after a packet is duplicated through an nft 'dup to' rule or another nf_dup_ipv4() / xt_TEE caller.
4) Improper control of a resource through its lifetime (CVE-ID: CVE-2026-46300)
CWE-ID: CWE-664 - Improper control of a resource through its lifetime
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause memory corruption.
The vulnerability exists due to improper state management in skb_try_coalesce() when transferring paged fragments during TCP receive coalescing. A local user can trigger packet processing that moves shared fragments into an unmarked skb to cause memory corruption.
The issue can lead ESP input to incorrectly treat an uncloned nonlinear skb as not having shared fragments and perform in-place decryption over externally owned or page-cache-backed fragments.
5) Improper access control (CVE-ID: CVE-2026-46333)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear
The vulnerability allows a local privileged user to disclose sensitive information.
The vulnerability exists due to improper access control in ptrace_may_access() when checking dumpability for tasks without an associated mm pointer. A local privileged user can inspect kernel thread details to disclose sensitive information.
The issue affects cases involving threads that no longer have a VM or never had one, such as kernel threads.
6) Double free (CVE-ID: CVE-2026-43494)
CWE-ID: CWE-415 - Double Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a double free in rds_message_zcopy_from_user() and rds_message_purge() when handling a zerocopy page pin failure during sendmsg processing. A local user can trigger a page pin failure and subsequent cleanup to cause a denial of service.
Remediation
Install update from vendor's website.