Ubuntu Security Advisories

Siebe Devroe, Héloïse Gollier, and Mathy Vanhoef discovered that the WiFi implementation in the Linux kernel did not properly handle aggregated frames in mesh networks, due to an incorrect fix for CVE-2020-24588. A physically proximate attacker could use this issue to inject packets. (CVE-2025-27558) Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - x86 architecture; - InfiniBand drivers; - Network drivers; - NVME drivers; - Ext4 file system; - SMB network file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Locking primitives; - IPv6 networking; - Multipath TCP; - Netfilter; - Open vSwitch; - SCTP protocol; - SMC sockets; (CVE-2026-31414, CVE-2026-31448, CVE-2026-31705, CVE-2026-43198, CVE-2026-43378, CVE-2026-43499, CVE-2026-46266, CVE-2026-46331, CVE-2026-52924, CVE-2026-52989, CVE-2026-53086, CVE-2026-53176, CVE-2026-53212, CVE-2026-53215, CVE-2026-53224, CVE-2026-53225, CVE-2026-53228, CVE-2026-53246, CVE-2026-53359, CVE-2026-64531)

Siebe Devroe, Héloïse Gollier, and Mathy Vanhoef discovered that the WiFi implementation in the Linux kernel did not properly handle aggregated frames in mesh networks, due to an incorrect fix for CVE-2020-24588. A physically proximate attacker could use this issue to inject packets. (CVE-2025-27558) Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - x86 architecture; - Cryptographic API; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - NVME drivers; - File systems infrastructure; - Ext4 file system; - OCFS2 file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Locking primitives; - B.A.T.M.A.N. meshing protocol; - Ceph Core library; - IPv6 networking; - Multipath TCP; - Netfilter; - SCTP protocol; - SMC sockets; - TIPC protocol; (CVE-2021-47378, CVE-2026-23392, CVE-2026-31405, CVE-2026-31414, CVE-2026-31448, CVE-2026-31657, CVE-2026-31668, CVE-2026-43071, CVE-2026-43198, CVE-2026-43493, CVE-2026-43499, CVE-2026-46266, CVE-2026-46331, CVE-2026-52914, CVE-2026-52924, CVE-2026-52931, CVE-2026-52955, CVE-2026-52958, CVE-2026-52982, CVE-2026-52986, CVE-2026-52989, CVE-2026-52993, CVE-2026-52999, CVE-2026-53002, CVE-2026-53006, CVE-2026-53043, CVE-2026-53045, CVE-2026-53088, CVE-2026-53176, CVE-2026-53212, CVE-2026-53224, CVE-2026-53225, CVE-2026-53228, CVE-2026-53246, CVE-2026-53309, CVE-2026-53359)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - OCFS2 file system; - SCTP protocol; (CVE-2026-53043, CVE-2026-53224, CVE-2026-53225, CVE-2026-53246, CVE-2026-53309)

Mark Bereza and Lilith Wyatt discovered that BioSig incorrectly handled certain crafted input files. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-22891, CVE-2026-20777)

It was discovered that pyasn1 did not properly bound the size of long-form tag identifiers when parsing BER, CER, or DER encoded data. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service. (CVE-2026-59884) It was discovered that pyasn1 processed OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service. (CVE-2026-59885) It was discovered that pyasn1 incorrectly handled conversion of decoded REAL values to Python float types. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU and memory resources, resulting in a denial of service. (CVE-2026-59886)

It was discovered that Libgcrypt had a timing-based side-channel flaw in its RSA implementation. A remote attacker could possibly use this issue to obtain sensitive information.

USN-8688-1 fixed a vulnerability in PAM. This update provides the corresponding fix for PAM on Ubuntu 26.04 LTS. Original advisory details: Juthawong Naisanguansee discovered that PAM incorrectly cleared failed login attempt records when certain services invoked the account phase without first performing authentication. An attacker could possibly use this issue to reset failed login counters, resulting in authentication lockout restrictions being bypassed.

USN-8555-1 fixed vulnerabilities in Ubuntu Advantage Tools. On Ubuntu 14.04 LTS only, it was discovered that some machines were unable to enable esm-infra-legacy due to a preemptive apt-helper check. This update fixes the problem. We apologize for the inconvenience. Original advisory details: Bilal Teke discovered that Ubuntu Advantage Tools exposed the Pro bearer token in command-line arguments when validating APT credentials. A local attacker could possibly use this issue to obtain sensitive information and gain unauthorized access to Ubuntu Pro repositories. (CVE-2026-9494) Frederick Jerusha discovered that Ubuntu Advantage Tools did not properly validate data received from the contract server when writing APT source files. An attacker could possibly use this issue to inject arbitrary APT configuration and execute arbitrary code. (CVE-2026-11386) Mateusz Gierblinski discovered that Ubuntu Advantage Tools did not properly handle symbolic links when collecting diagnostic logs. A local attacker could possibly use this issue to obtain sensitive information from files owned by the administrator. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-12391)

Alexis Challande discovered that libevent incorrectly handled certain empty output buffers. An attacker could possibly use this issue to trigger a use-after-free, resulting in a denial of service or arbitrary code execution. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-63381) Rajat Raghav discovered that libevent incorrectly handled certain HTTP requests. An attacker could possibly use this issue to desynchronize HTTP request boundaries, resulting in HTTP request smuggling. (CVE-2026-63382) Qiu Sihao discovered that libevent incorrectly handled certain malformed tagged RPC data. An attacker could possibly use this issue to trigger an out-of-bounds read, resulting in a denial of service. (CVE-2026-63383) Qiu Sihao discovered that libevent incorrectly handled certain large payload lengths in tagged RPC data. An attacker could possibly use this issue to consume excessive system resources, resulting in a denial of service. (CVE-2026-63384) Asaf Meizner discovered that libevent incorrectly handled certain HTTP URIs and header values. An attacker could possibly use this issue to cause HTTP messages to be interpreted inconsistently, resulting in security restrictions being bypassed. (CVE-2026-63385)

It was discovered that ncurses incorrectly handled specially crafted terminfo database entries. A local attacker could possibly use this issue to cause applications using ncurses to crash, resulting in a denial of service.

It was discovered that sudo-rs incorrectly handled time-of-check vs time- of-use conditions in sudoedit. A local attacker with permission to edit specific files using sudoedit could use this issue to place files in arbitrary directories, and possibly escalate their privileges. This issue only affected systems configured to grant fine-grained sudoedit file editing permissions, which is not the default configuration.

It was discovered that Pillow did not properly manage memory when processing certain image files. An attacker could possibly use this issue to cause a denial of service or read sensitive data.

USN-8705-1 fixed vulnerabilities in OpenZFS. This update provides the corresponding fix for OpenZFS on Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. Original advisory details: It was discovered that OpenZFS incorrectly handled authorization checks for certain ioctl operations on Linux. A local attacker could possibly use this issue to perform pool-administrative operations or access privileged information, resulting in an authorization bypass.

It was discovered that zlib incorrectly handled negative length parameters in CRC32 combine functions. An attacker could use this issue to cause a denial of service via excessive CPU consumption.

It was discovered that primitive decoders in openCryptoki produced integer underflows when the encoded length was zero. An attacker could possibly use this issue to trigger out-of-bounds reads. (CVE-2026-40253) It was discovered that openCryptoki incorrectly handled symlinks. An attacker in the token-group could possibly use this issue to achieve privilege escalation or access sensitive information. (CVE-2026-23893) It was discovered that the CKM_ECDH_AES_KEY_WRAP implementation had a heap buffer overflow vulnerability. An attacker could possibly use this issue to trigger heap corruption, or denial-of-service. (CVE-2026-22791)

It was discovered that cpio incorrectly sanitized hard-link targets when extracting tar archives in copy-in mode. If a user or automated system were tricked into extracting a specially crafted tar archive, an attacker could possibly use this issue to create hard links to files outside the extraction directory, even when using the --no-absolute-filenames option. (CVE-2026-66484) It was discovered that cpio did not properly bound the stack memory allocated for pathnames during archive extraction. If a user or automated system were tricked into extracting a specially crafted cpio archive, an attacker could possibly use this issue to cause cpio to crash, resulting in a denial of service. (CVE-2026-66485) It was discovered that cpio did not properly escape archive member names when listing archive contents. If a user or automated system were tricked into listing a specially crafted archive, an attacker could possibly use this issue to inject misleading output or malicious terminal control sequences. (CVE-2026-66486)

It was discovered that OpenZFS incorrectly handled authorization checks for certain ioctl operations on Linux. A local attacker could possibly use this issue to perform pool-administrative operations or access privileged information, resulting in an authorization bypass.

Several security issues were discovered in the WebKitGTK Web and JavaScript engines. If a user were tricked into viewing a malicious website, a remote attacker could exploit a variety of issues related to web browser security, including cross-site scripting attacks, denial of service attacks, and arbitrary code execution.

It was discovered that libblkid in util-linux had a heap use-after-free vulnerability during nested partition probing. An attacker who could present a crafted block device image could possibly use this issue to obtain sensitive information or cause a denial of service. (CVE-2026-13595) It was discovered that the mount utility in util-linux had a time-of-check- time-of-use vulnerability when setting up loop devices. A local attacker could possibly use this issue to obtain unauthorized read access to root- protected files and block devices. (CVE-2026-27456) It was discovered that the login utility in util-linux improperly canonicalized hostnames when invoked with the -h option. A remote attacker could possibly use this issue to bypass host-based access control rules. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-3184) It was discovered that libmount in util-linux had a time-of-check-time-of- use vulnerability in its ownership hook. A local attacker could possibly use this issue to gain elevated privileges. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-53612) It was discovered that libmount in util-linux had a time-of-check-time-of- use vulnerability that allowed target path redirection during mount operations. A local attacker could possibly use this issue to gain elevated privileges. (CVE-2026-53613) It was discovered that libmount in util-linux improperly handled the LIBMOUNT_FORCE_MOUNT2 environment variable in the SUID mount utility. A local attacker could possibly use this issue to bypass nosuid and noexec mount options and gain elevated privileges. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-53614) It was discovered that libblkid in util-linux had an integer overflow vulnerability when parsing DOS partition tables. An attacker who could present a crafted block device image could possibly use this issue to cause a denial of service. (CVE-2026-53615)

It was discovered that UDisks did not correctly validate the caller identity when handling the as-user option in the org.freedesktop.UDisks2.Filesystem.Mount() D-Bus method. A local attacker with an active console session could possibly use this issue to mount filesystems on behalf of arbitrary users, including privileged accounts, leading to local privilege escalation.