SB2026081892 - Ubuntu update for linux
Published: August 18, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Improper input validation (CVE-ID: CVE-2026-64531)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 6.8 [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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper handling of oversized nested action attributes in openvswitch flow action construction when processing user-supplied openvswitch nested action attributes. A local user can supply specially crafted nested CLONE or CT actions to cause a denial of service.
The issue occurs because a generated nested action attribute can be closed with a truncated nla_len, causing later dump or teardown operations to walk a structurally different action stream than the one that was validated.
2) Use-after-free (CVE-ID: CVE-2026-53247)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 6.8 [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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in the mtk_eth_soc driver metadata dst teardown path when tearing down the device while packets still hold a non-refcounted pointer to metadata_dst. A local user can trigger the teardown condition to cause a denial of service.
The issue arises in the RX path because skb_dst_set_noref() requires RCU read-side protection and the destination object must remain valid until all RCU readers have completed.
3) Out-of-bounds read (CVE-ID: CVE-2026-53246)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to disclose sensitive information or cause memory corruption.
The vulnerability exists due to an out-of-bounds read in sctp_unpack_cookie() and cached peer INIT chunk processing when processing a crafted COOKIE_ECHO chunk. A remote attacker can send a specially crafted COOKIE_ECHO chunk with an inflated cached INIT chunk length to disclose sensitive information or cause memory corruption.
The issue occurs in a listening SCTP server while walking parameters from the cached peer INIT chunk embedded after the cookie.
4) Out-of-bounds read (CVE-ID: CVE-2026-53224)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to out-of-bounds read in SCTP cookie processing in sctp_unpack_cookie(), sctp_process_init(), and sctp_raw_to_bind_addrs() when handling a malformed COOKIE_ECHO containing a truncated embedded INIT chunk or malformed address parameters. A remote attacker can send a specially crafted COOKIE_ECHO to cause a denial of service.
When cookie authentication is disabled, an oversized raw address list length can also be used to trigger the out-of-bounds read condition.
Remediation
Install update from vendor's website.