Ubuntu Security Advisories

It was discovered that BuildKit, contained within Docker, incorrectly handled file path validation when processing frontend API messages. An attacker could possibly use this issue to write files outside of the intended state directory. (CVE-2026-33747) It was discovered that BuildKit, contained within Docker, incorrectly validated the subdir component of Git URL fragments. An attacker could possibly use this issue to access files outside of the checked-out repository root. (CVE-2026-33748)

It was discovered that Mako incorrectly handled URIs with double-slash prefixes in TemplateLookup. A remote attacker could possibly use this issue to obtain sensitive information.

Andrew MacPherson discovered that nghttp2 did not properly validate internal state when the session termination API was called. A remote attacker could possibly use this issue to cause nghttp2 to crash, resulting in a denial of service.

It was discovered that Django did not vary cached response headers on cookies when sessions were not modified while SESSION_SAVE_EVERY_REQUEST was enabled. A remote attacker could possibly use this issue to steal a user's session. (CVE-2026-35192) Kyle Agronick and Jacob Walls discovered that Django incorrectly handled ASGI requests with missing or understated Content-Length header values. A remote attacker could possibly use this issue to cause Django to use excessive resources, leading to a denial of service. (CVE-2026-5766) Ahmad Sadeddin discovered that Django UpdateCacheMiddleware incorrectly cached requests where the Vary header contained an asterisk. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6907)

Michał Majchrowicz and Marcin Wyczechowski discovered that sed incorrectly handled symbolic links when performing in-place edits. A local attacker could possibly use this issue to overwrite arbitrary files.

It was discovered that Exim incorrectly handled parsing malformed JSON in message headers. A remote attacker could possibly use this issue to execute arbitrary code. (CVE-2026-40685) It was discovered that Exim incorrectly handled processing of UTF-8 trailing characters. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-40686) It was discovered that Exim incorrectly handled SPA authenticator input. An authenticated user could possibly use this issue to execute arbitrary code. (CVE-2026-40687)

It was discovered that curl incorrectly reused non-TLS connections when TLS was required in some STARTTLS configurations. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-4873) It was discovered that curl incorrectly reused certain HTTP Negotiate connections. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-5545) It was discovered that curl incorrectly reused certain SMB connections. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-5773) It was discovered that curl could leak proxy credentials when handling redirects in some configurations. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6253) It was discovered that curl could leak cookies because of stale custom cookie host handling in some requests. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6276) It was discovered that curl could leak .netrc credentials when reusing proxy connections in some situations. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6429) It was discovered that curl could leak Digest authentication state when switching proxies in some situations. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-7168)

USN-8226-1 added a mitigation to kmod to disable loading the algif_aead module. This update adds the same mitigation to Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. Original advisory details: It was discovered that the Linux kernel algif_aead module contained a logic flaw allowing a local attacker to escalate privileges to root. This update to the kmod package disables loading the algif_aead module as a measure to mitigate the issue until kernel updates are made available. See the following URL for more information https://ubuntu.com/blog/copy-fail-vulnerability-fixes-available

It was discovered that the Linux kernel algif_aead module contained a logic flaw allowing a local attacker to escalate privileges to root. This update to the kmod package disables loading the algif_aead module as a measure to mitigate the issue until kernel updates are made available. See the following URL for more information https://ubuntu.com/blog/copy-fail-vulnerability-fixes-available

Aaron Rainbolt discovered that zuluCrypt used insecure PolicyKit settings in zuluPolkit. An attacker could possibly use this issue to cause local privilege escalation to root. (CVE-2025-53391)

Jared Deckard discovered that Python marshmallow did not correctly handle hiding certain fields. An attacker could possibly use this issue to leak sensitive information. This issue only affected Ubuntu 18.04 LTS. (CVE-2018-17175) It was discovered that Python marshmallow did not efficiently handle merging certain objects. An attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2025-68480)

It was discovered that Roundcube Webmail mishandled Punycode xn-- domain names. An attacker could possibly use this issue to cause a homograph attack. (CVE-2019-15237) It was discovered that Roundcube Webmail did not properly sanitize certain attributes when handling CSS within HTML messages and certain SVG attributes. An attacker could possibly use this issue to cause a cross-site scripting attack. (CVE-2024-38356, CVE-2024-38357) It was discovered that Roundcube Webmail did not properly sanitize certain HTML attributes when rendering e-mail messages. An attacker could possibly use this issue to cause a cross-site scripting attack. (CVE-2024-42008) It was discovered that Roundcube Webmail did not properly filter certain CSS token sequences within rendered e-mail messages. An attacker could possibly use this issue to obtain sensitive information. (CVE-2024-42010) It was discovered that Roundcube Webmail did not properly treat an SVG tag as an image source within its HTML sanitizer. An attacker could possibly use this issue to bypass remote image blocking to track email open actions or potentially bypass access control. (CVE-2026-25916) It was discovered that Roundcube Webmail did not properly handle comments within Cascading Style Sheets (CSS). An attacker could possibly use this issue to perform a CSS injection attack. (CVE-2026-26079)

Qualys discovered that several vulnerabilities existed in the AppArmor Linux kernel Security Module (LSM). An unprivileged local attacker could use these issues to load, replace, and remove arbitrary AppArmor profiles causing denial of service, exposure of sensitive information (kernel memory), local privilege escalation, or possibly escape a container. (LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403, CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407, CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411) 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: - ARM64 architecture; - x86 architecture; - Cryptographic API; - GPU drivers; - I2C subsystem; - BTRFS file system; - XFRM subsystem; - Padata parallel execution mechanism; - IPv4 networking; - IPv6 networking; - MAC80211 subsystem; - Netfilter; - Network traffic control; - SMC sockets; (CVE-2021-47599, CVE-2022-48875, CVE-2022-49046, CVE-2022-49698, CVE-2024-46816, CVE-2024-49927, CVE-2024-56640, CVE-2025-21726, CVE-2025-21780, CVE-2025-37849, CVE-2025-40019, CVE-2025-40215, CVE-2026-23060, CVE-2026-23074)

Christos Papakonstantinou discovered that the OpenSSH scp tool incorrectly handled the legacy scp protocol (-O) option. This could result in certain files being installed setuid or setgid, contrary to expectations. (CVE-2026-35385) Florian Kohnhäuser discovered that OpenSSH incorrectly handled shell metacharacters in usernames within a command line. When untrusted usernames and non-default configurations using % in ssh_config are being used, an attacker could possibly use this issue to execute arbitrary code. (CVE-2026-35386) Christos Papakonstantinou discovered that OpenSSH incorrectly handled parsing the PubkeyAcceptedAlgorithms and HostbasedAcceptedAlgorithms options. This could result in unintended ECDSA algorithms being used, contrary to expectations. (CVE-2026-35387) Michalis Vasileiadis discovered that OpenSSH incorrectly handled proxy-mode multiplexing sessions. This could result in no confirmation being asked, contrary to expectations. (CVE-2026-35388) Vladimir Tokarev discovered that OpenSSH incorrectly handled certificates with the principal name containing a comma character when using user-trusted CA keys in authorized_keys and an authorized_keys principals="" option that lists more than one principal. This could result in inappropriate principal matching, contrary to expectations. (CVE-2026-35414)

USN-8195-1 fixed a vulnerability in PackageKit. This update provides the corresponding fix to Ubuntu 16.04 LTS, Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. Original advisory details: It was discovered that PackageKit incorrectly handled certain transactions. A local attacker could use this issue to install arbitrary packages as root, possibly resulting in privilege escalation.

It was discovered that wheel did not correctly handle certain file paths. If a user or automated system were tricked into opening a specially crafted file, an attacker could possibly use this issue to execute arbitrary code.

USN-8198-1 fixed vulnerabilities in Tornado. This update provides the corresponding updates for Ubuntu 26.04 LTS. Original advisory details: It was discovered that Tornado incorrectly handled parsing of large multipart request bodies. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-31958) It was discovered that Tornado did not properly validate characters in cookie values. An attacker could possibly use this issue to inject arbitrary cookie attributes. (CVE-2026-35536)

Cameron Criswell discovered that UltraJSON contained a memory leak that would occur when parsing large integers. An attacker could possibly use this issue to cause UltraJSON to crash, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-32874) It was discovered that UltraJSON contained integer overflow/underflow issues when calculating how much memory to reserve for indentation in certain instances. An attacker could possibly use this issue to cause UltraJSON to crash, resulting in a denial of service. (CVE-2026-32875)

Josh Eads, Kristoffer Janke, Eduardo Vela Nava, Tavis Ormandy, and Matteo Rizzo discovered that some AMD Zen processors did not properly verify the signature of CPU microcode. This flaw is known as EntrySign. A privileged attacker could possibly use this issue to cause load malicious CPU microcode causing loss of integrity and confidentiality. (CVE-2024-36347) 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: - MIPS architecture; - PowerPC architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - ACPI drivers; - Network block device driver; - Bluetooth drivers; - Character device driver; - TPM device driver; - Clock framework and drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - GPU drivers; - Hardware monitoring drivers; - InfiniBand drivers; - Input Device core drivers; - IOMMU subsystem; - IRQ chip drivers; - Macintosh device drivers; - Multiple devices driver; - Media drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - Ethernet team driver; - MediaTek network drivers; - NVME drivers; - PA-RISC drivers; - Chrome hardware platform drivers; - x86 platform drivers; - Voltage and Current Regulator drivers; - SCSI subsystem; - SPI subsystem; - Media Oriented Systems Transport (MOST) driver; - Realtek RTL8723BS SDIO drivers; - TCM subsystem; - USB Host Controller drivers; - USB Type-C Connector System Software Interface driver; - Backlight driver; - Watchdog drivers; - BFS file system; - BTRFS file system; - Ext4 file system; - F2FS file system; - FUSE (File system in Userspace); - HFS+ file system; - File systems infrastructure; - Journaling layer for block devices (JBD2); - Network file system (NFS) client; - File system notification infrastructure; - NTFS3 file system; - OCFS2 file system; - SMB network file system; - BPF subsystem; - Ethernet bridge; - io_uring subsystem; - Locking primitives; - Scheduler infrastructure; - Shadow Call Stack mechanism; - Tracing infrastructure; - Memory management; - CAIF protocol; - Ceph Core library; - Networking core; - Ethtool driver; - Handshake API; - HSR network protocol; - IPv4 networking; - IPv6 networking; - MAC80211 subsystem; - Multipath TCP; - Netfilter; - NET/ROM layer; - NFC subsystem; - Open vSwitch; - Rose network layer; - Network traffic control; - Network sockets; - Sun RPC protocol; - Integrity Measurement Architecture(IMA) framework; - Key management; - Simplified Mandatory Access Control Kernel framework; - FireWire sound drivers; - HD-audio driver; - Turtle Beach Wavefront ALSA driver; - STMicroelectronics SoC drivers; - USB sound devices; - KVM subsystem; (CVE-2024-57795, CVE-2025-22022, CVE-2025-22111, CVE-2025-38022, CVE-2025-38234, CVE-2025-40164, CVE-2025-40325, CVE-2025-68206, CVE-2025-68254, CVE-2025-68255, CVE-2025-68256, CVE-2025-68257, CVE-2025-68258, CVE-2025-68259, CVE-2025-68261, CVE-2025-68263, CVE-2025-68264, CVE-2025-68265, CVE-2025-68266, CVE-2025-68291, CVE-2025-68325, CVE-2025-68332, CVE-2025-68335, CVE-2025-68336, CVE-2025-68337, CVE-2025-68344, CVE-2025-68345, CVE-2025-68346, CVE-2025-68347, CVE-2025-68349, CVE-2025-68354, CVE-2025-68362, CVE-2025-68363, CVE-2025-68364, CVE-2025-68366, CVE-2025-68367, CVE-2025-68369, CVE-2025-68371, CVE-2025-68372, CVE-2025-68374, CVE-2025-68378, CVE-2025-68379, CVE-2025-68380, CVE-2025-68724, CVE-2025-68727, CVE-2025-68728, CVE-2025-68732, CVE-2025-68733, CVE-2025-68740, CVE-2025-68741, CVE-2025-68742, CVE-2025-68744, CVE-2025-68753, CVE-2025-68755, CVE-2025-68756, CVE-2025-68757, CVE-2025-68758, CVE-2025-68759, CVE-2025-68763, CVE-2025-68764, CVE-2025-68765, CVE-2025-68766, CVE-2025-68767, CVE-2025-68769, CVE-2025-68770, CVE-2025-68771, CVE-2025-68772, CVE-2025-68773, CVE-2025-68774, CVE-2025-68775, CVE-2025-68776, CVE-2025-68777, CVE-2025-68778, CVE-2025-68780, CVE-2025-68782, CVE-2025-68783, CVE-2025-68785, CVE-2025-68786, CVE-2025-68787, CVE-2025-68788, CVE-2025-68794, CVE-2025-68795, CVE-2025-68796, CVE-2025-68797, CVE-2025-68798, CVE-2025-68799, CVE-2025-68800, CVE-2025-68801, CVE-2025-68804, CVE-2025-68806, CVE-2025-68808, CVE-2025-68809, CVE-2025-68810, CVE-2025-68811, CVE-2025-68813, CVE-2025-68814, CVE-2025-68815, CVE-2025-68816, CVE-2025-68817, CVE-2025-68818, CVE-2025-68819, CVE-2025-68820, CVE-2025-68821, CVE-2025-71064, CVE-2025-71065, CVE-2025-71066, CVE-2025-71067, CVE-2025-71068, CVE-2025-71069, CVE-2025-71071, CVE-2025-71072, CVE-2025-71075, CVE-2025-71077, CVE-2025-71078, CVE-2025-71079, CVE-2025-71081, CVE-2025-71082, CVE-2025-71083, CVE-2025-71084, CVE-2025-71085, CVE-2025-71086, CVE-2025-71087, CVE-2025-71088, CVE-2025-71089, CVE-2025-71091, CVE-2025-71093, CVE-2025-71094, CVE-2025-71095, CVE-2025-71096, CVE-2025-71097, CVE-2025-71098, CVE-2025-71101, CVE-2025-71102, CVE-2025-71104, CVE-2025-71105, CVE-2025-71107, CVE-2025-71108, CVE-2025-71109, CVE-2025-71111, CVE-2025-71112, CVE-2025-71113, CVE-2025-71114, CVE-2025-71116, CVE-2025-71118, CVE-2025-71119, CVE-2025-71120, CVE-2025-71121, CVE-2025-71122, CVE-2025-71123, CVE-2025-71125, CVE-2025-71126, CVE-2025-71127, CVE-2025-71130, CVE-2025-71131, CVE-2025-71132, CVE-2025-71133, CVE-2025-71135, CVE-2025-71136, CVE-2025-71137, CVE-2025-71138, CVE-2025-71140, CVE-2025-71141, CVE-2025-71143, CVE-2025-71144, CVE-2025-71147, CVE-2025-71148, CVE-2025-71149, CVE-2025-71150, CVE-2025-71151, CVE-2025-71153, CVE-2025-71154, CVE-2026-23209)

It was discovered that follow-redirects did not properly protect sensitive user information during redirects. An attacker could possibly use this issue to expose sensitive information. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2022-0155) It was discovered that follow-redirects did not properly remove sensitive information before storage or transfer. An attacker could possibly use this issue to expose sensitive information. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2022-0536) It was discovered that follow-redirects did not properly validate URLs when handling certain inputs. An attacker could possibly use this issue to redirect users to a malicious site, resulting in information disclosure or phishing attacks. (CVE-2023-26159) It was discovered that follow-redirects did not properly clear proxy authentication headers during cross-domain redirects. An attacker could possibly use this issue to cause exposure of sensitive credentials. (CVE-2024-28849)