In the Linux kernel, the following vulnerability has been resolved: flow_dissector: avoid u16 truncation of skb->len when computing thoff __skb_flow_dissect() computes key_control->thoff using: key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); min_t(u16, ...) casts both arguments to u16 before comparing them. Whenever skb->len (or hlen) modulo 65536 is smaller than nhoff, the truncated length wins and thoff is set to a bogus small value, even when the dissection succeeded. For example, an IPv4/TCP frame with skb->len == 65540 and nhoff == 34 gets thoff == 4, so callers such as skb_probe_transport_header() point the transport header inside the Ethernet header. Such skbs are not exotic: - At the time of commit d0c081b49137 ("flow_dissector: properly cap thoff field"), AF_PACKET with PACKET_VNET_HDR could already build GSO skbs larger than 64KB (MTU checks are skipped for GSO, and alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0 pages on top of the linear part). - BIG TCP now makes skbs larger than 64KB common. - The following patch makes tun_get_user() dissect IFF_TAP frames before eth_type_trans() pulls the Ethernet header, so a GSO frame carrying a 65522..65535 byte L3 packet will be dissected with skb->len in [65536, 65549]. Compare as u32 instead. If the resulting offset cannot be represented in the u16 key_control->thoff, cap it to U16_MAX and report the dissection as failed rather than silently returning a wrong transport offset. thoff is still set on failure, as some callers (such as eth_get_headlen()) use it regardless of the return value.

The remote Ubuntu 26.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-9018-1 advisory.

    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:

    - Network file systems library;

    - Stream parser;

    - ARM64 architecture;

    - PowerPC architecture;

    - RISC-V architecture;

    - S390 architecture;

    - User-Mode Linux (UML);

    - x86 architecture;

    - Block layer subsystem;

    - Android drivers;

    - Bluetooth drivers;

    - TPM device driver;

    - DPLL subsystem;

    - EDAC drivers;

    - GPIO subsystem;

    - GPU drivers;

    - HID subsystem;

    - IIO subsystem;

    - IIO ADC drivers;

    - InfiniBand drivers;

    - Input Device (Miscellaneous) drivers;

    - Multiple devices driver;

    - MemoryStick subsystem;

    - MMC subsystem;

    - MTD block device drivers;

    - Network drivers;

    - Ethernet bonding driver;

    - Mellanox network drivers;

    - STMicroelectronics network drivers;

    - Ethernet team driver;

    - MediaTek network drivers;

    - NVME drivers;

    - Device tree and open firmware driver;

    - Power sequencing drivers;

    - Voltage and Current Regulator drivers;

    - Real Time Clock drivers;

    - SCSI subsystem;

    - Greybus lights staging drivers;

    - Trusted Execution Environment drivers;

    - Thunderbolt and USB4 drivers;

    - TTY drivers;

    - Cadence USB3 driver;

    - USB Device Class drivers;

    - USB core drivers;

    - DesignWare USB2 driver;

    - DesignWare USB3 driver;

    - USB Gadget drivers;

    - USB Serial drivers;

    - USB Mass Storage drivers;

    - USB Type-C support driver;

    - USB Type-C Port Controller Manager driver;

    - TI TPS6598x USB Power Delivery controller driver;

    - USB Type-C Connector System Software Interface driver;

    - Amazon Nitro Enclaves driver;

    - Virtual machine generation ID driver;

    - BTRFS file system;

    - File systems infrastructure;

    - SMB network file system;

    - XFS file system;

    - BPF subsystem;

    - io_uring subsystem;

    - Netfilter;

    - Namespaces infrastructure;

    - Networking core;

    - Networking subsytem;

    - Virtio network driver;

    - Bluetooth subsystem;

    - IPv4 networking;

    - Network traffic control;

    - Audit subsystem;

    - Control group (cgroup);

    - Perf events;

    - Kernel fork() syscall;

    - Kernel futex primitives;

    - KProbes tracing;

    - Kexec HandOver (KHO);

    - Kernel module support;

    - Tracing infrastructure;

    - Workqueue subsystem;

    - Memory management;

    - Ethernet bridge;

    - Devlink API;

    - IPv6 networking;

    - MAC80211 subsystem;

    - Management Component Transport Protocol (MCTP);

    - Open vSwitch;

    - Packet sockets;

    - SCTP protocol;

    - SMC sockets;

    - TIPC protocol;

    - VMware vSockets driver;

    - Wireless networking;

    - XFRM subsystem;

    - Drivers core;

    - Key management;

    - SELinux security module;

    - ALSA framework;

    - Creative Sound Blaster X-Fi driver;

    - Analog Devices audio codecs;

    - Maxim audio codecs;

    - Realtek audio codecs;

    - QCOM ASoC drivers;

    - Samsung ASoC drivers;

    - SoundWire (SDCA) ASoC drivers;

    - USB sound devices; (CVE-2026-68305, CVE-2026-72404, CVE-2026-72497, CVE-2026-74527, CVE-2026-74568,     CVE-2026-89568, CVE-2026-89764, CVE-2026-89907, CVE-2026-90144, CVE-2026-90155, CVE-2026-90162,     CVE-2026-90167, CVE-2026-90317, CVE-2026-93175, CVE-2026-98038, CVE-2026-98375, CVE-2026-98432,     CVE-2026-98655, CVE-2026-98656, CVE-2026-98657, CVE-2026-98658, CVE-2026-98659, CVE-2026-98660,     CVE-2026-98661, CVE-2026-98662, CVE-2026-98663, CVE-2026-98664, CVE-2026-98665, CVE-2026-98666,     CVE-2026-98667, CVE-2026-98668, CVE-2026-98669, CVE-2026-98670, CVE-2026-98671, CVE-2026-98672,     CVE-2026-98673, CVE-2026-98674, CVE-2026-98675, CVE-2026-98676, CVE-2026-98677, CVE-2026-98678,     CVE-2026-98679, CVE-2026-98680, CVE-2026-98681, CVE-2026-98682, CVE-2026-98683, CVE-2026-98684,     CVE-2026-98685, CVE-2026-98686, CVE-2026-98687, CVE-2026-98689, CVE-2026-98690, CVE-2026-98691,     CVE-2026-98692, CVE-2026-98693, CVE-2026-98694, CVE-2026-98695, CVE-2026-98696, CVE-2026-98697,     CVE-2026-98698, CVE-2026-98699, CVE-2026-98700, CVE-2026-98701, CVE-2026-98702, CVE-2026-98703,     CVE-2026-98704, CVE-2026-98705, CVE-2026-98706, CVE-2026-98707, CVE-2026-98708, CVE-2026-98709,     CVE-2026-98710, CVE-2026-98711, CVE-2026-98712, CVE-2026-98713, CVE-2026-98714, CVE-2026-98715,     CVE-2026-98716, CVE-2026-98717, CVE-2026-98718, CVE-2026-98719, CVE-2026-98720, CVE-2026-98721,     CVE-2026-98722, CVE-2026-98723, CVE-2026-98724, CVE-2026-98725, CVE-2026-98726, CVE-2026-98727,     CVE-2026-98728, CVE-2026-98729, CVE-2026-98730, CVE-2026-98731, CVE-2026-98732, CVE-2026-98733,     CVE-2026-98734, CVE-2026-98735, CVE-2026-98736, CVE-2026-98737, CVE-2026-98738, CVE-2026-98739,     CVE-2026-98740, CVE-2026-98741, CVE-2026-98742, CVE-2026-98743, CVE-2026-98744, CVE-2026-98745,     CVE-2026-98746, CVE-2026-98747, CVE-2026-98748, CVE-2026-98749, CVE-2026-98750, CVE-2026-98751,     CVE-2026-98752, CVE-2026-98753, CVE-2026-98754, CVE-2026-98755, CVE-2026-98756, CVE-2026-98757,     CVE-2026-98758, CVE-2026-98759, CVE-2026-98760, CVE-2026-98761, CVE-2026-98762, CVE-2026-98763,     CVE-2026-98764, CVE-2026-98765, CVE-2026-98766, CVE-2026-98767, CVE-2026-98768, CVE-2026-98769,     CVE-2026-98770, CVE-2026-98771, CVE-2026-98772, CVE-2026-98773, CVE-2026-98774, CVE-2026-98775,     CVE-2026-98776, CVE-2026-98777, CVE-2026-98778, CVE-2026-98779, CVE-2026-98780, CVE-2026-98781,     CVE-2026-98782, CVE-2026-98783, CVE-2026-98784, CVE-2026-98785, CVE-2026-98786, CVE-2026-98788,     CVE-2026-98789, CVE-2026-98790, CVE-2026-98791, CVE-2026-98792, CVE-2026-98793, CVE-2026-98794,     CVE-2026-98795, CVE-2026-98796, CVE-2026-98797, CVE-2026-98798, CVE-2026-98799, CVE-2026-98800,     CVE-2026-98801, CVE-2026-98802, CVE-2026-98803, CVE-2026-98804, CVE-2026-98805, CVE-2026-98806,     CVE-2026-98807, CVE-2026-98808, CVE-2026-98809, CVE-2026-98810, CVE-2026-98811, CVE-2026-98812,     CVE-2026-98813, CVE-2026-98814, CVE-2026-98816, CVE-2026-98817, CVE-2026-98818, CVE-2026-98819,     CVE-2026-98820, CVE-2026-98821, CVE-2026-98822, CVE-2026-98823, CVE-2026-98824, CVE-2026-98825,     CVE-2026-98826, CVE-2026-98827, CVE-2026-98828, CVE-2026-98829, CVE-2026-98830, CVE-2026-98831,     CVE-2026-98833, CVE-2026-98834, CVE-2026-98835, CVE-2026-98836, CVE-2026-98837, CVE-2026-98838,     CVE-2026-98839, CVE-2026-98840, CVE-2026-98841, CVE-2026-98842, CVE-2026-98843, CVE-2026-98844,     CVE-2026-98845, CVE-2026-98846, CVE-2026-98847, CVE-2026-98848, CVE-2026-98849, CVE-2026-98850,     CVE-2026-98851, CVE-2026-98852, CVE-2026-98853, CVE-2026-98854, CVE-2026-98855, CVE-2026-98856,     CVE-2026-98857, CVE-2026-98858, CVE-2026-98859, CVE-2026-98860, CVE-2026-98861, CVE-2026-98862,     CVE-2026-98863, CVE-2026-98931, CVE-2026-98932, CVE-2026-98933, CVE-2026-98934, CVE-2026-98935,     CVE-2026-98936, CVE-2026-98937, CVE-2026-98939, CVE-2026-98940, CVE-2026-98944, CVE-2026-98945,     CVE-2026-98946, CVE-2026-98947, CVE-2026-98948, CVE-2026-98949, CVE-2026-98950, CVE-2026-98951,     CVE-2026-98952, CVE-2026-98953, CVE-2026-98954, CVE-2026-98955, CVE-2026-98956, CVE-2026-98957,     CVE-2026-98958, CVE-2026-98959, CVE-2026-98960, CVE-2026-98961, CVE-2026-98962, CVE-2026-98963,     CVE-2026-98964, CVE-2026-98965, CVE-2026-98966, CVE-2026-98967, CVE-2026-98968, CVE-2026-98969,     CVE-2026-98970, CVE-2026-98971, CVE-2026-98972, CVE-2026-98973, CVE-2026-98974, CVE-2026-98975,     CVE-2026-98977, CVE-2026-98978, CVE-2026-98979, CVE-2026-98980, CVE-2026-98981, CVE-2026-98982,     CVE-2026-98983, CVE-2026-98984, CVE-2026-98985, CVE-2026-98986, CVE-2026-98987, CVE-2026-98988,     CVE-2026-98989, CVE-2026-98990, CVE-2026-98991, CVE-2026-98992, CVE-2026-98993, CVE-2026-98994,     CVE-2026-98995, CVE-2026-98996, CVE-2026-98997, CVE-2026-98999, CVE-2026-99000, CVE-2026-99001,     CVE-2026-99002, CVE-2026-99003, CVE-2026-99004, CVE-2026-99005, CVE-2026-99006, CVE-2026-99007,     CVE-2026-99008, CVE-2026-99009, CVE-2026-99010, CVE-2026-99011, CVE-2026-99012, CVE-2026-99013,     CVE-2026-99014, CVE-2026-99015, CVE-2026-99016, CVE-2026-99017, CVE-2026-99018, CVE-2026-99019,     CVE-2026-99020, CVE-2026-99021, CVE-2026-99022, CVE-2026-99023, CVE-2026-99024, CVE-2026-99025,     CVE-2026-99026, CVE-2026-99027, CVE-2026-99028, CVE-2026-99029, CVE-2026-99030, CVE-2026-99031,     CVE-2026-99032, CVE-2026-99033, CVE-2026-99034, CVE-2026-99035, CVE-2026-99036, CVE-2026-99037,     CVE-2026-99038, CVE-2026-99039, CVE-2026-99040, CVE-2026-99041, CVE-2026-99043, CVE-2026-99044,     CVE-2026-99045, CVE-2026-99046, CVE-2026-99047, CVE-2026-99048, CVE-2026-99049, CVE-2026-99050,     CVE-2026-99051, CVE-2026-99052, CVE-2026-99053, CVE-2026-99054, CVE-2026-99055, CVE-2026-99056,     CVE-2026-99057, CVE-2026-99058, CVE-2026-99059, CVE-2026-99060, CVE-2026-99061, CVE-2026-99062,     CVE-2026-99063, CVE-2026-99064, CVE-2026-99065, CVE-2026-99066, CVE-2026-99067, CVE-2026-99068,     CVE-2026-99069, CVE-2026-99070, CVE-2026-99071, CVE-2026-99072, CVE-2026-99073, CVE-2026-99074,     CVE-2026-99075, CVE-2026-99076, CVE-2026-99077, CVE-2026-99078, CVE-2026-99079, CVE-2026-99080,     CVE-2026-99081, CVE-2026-99088, CVE-2026-99089, CVE-2026-99090, CVE-2026-99091, CVE-2026-99092,     CVE-2026-99093, CVE-2026-99094, CVE-2026-99095, CVE-2026-99096, CVE-2026-99097, CVE-2026-99098,     CVE-2026-99099, CVE-2026-99999)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

An update of the linux package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - flow_dissector: avoid u16 truncation of skb->len when computing thoff __skb_flow_dissect() computes     key_control->thoff using: key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); min_t(u16, ...)     casts both arguments to u16 before comparing them. Whenever skb->len (or hlen) modulo 65536 is smaller     than nhoff, the truncated length wins and thoff is set to a bogus small value, even when the dissection     succeeded. For example, an IPv4/TCP frame with skb->len == 65540 and nhoff == 34 gets thoff == 4, so     callers such as skb_probe_transport_header() point the transport header inside the Ethernet header. Such     skbs are not exotic: - At the time of commit d0c081b49137 (flow_dissector: properly cap thoff field),     AF_PACKET with PACKET_VNET_HDR could already build GSO skbs larger than 64KB (MTU checks are skipped for     GSO, and alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0 pages on top of the linear     part). - BIG TCP now makes skbs larger than 64KB common. - The following patch makes tun_get_user()     dissect IFF_TAP frames before eth_type_trans() pulls the Ethernet header, so a GSO frame carrying a     65522..65535 byte L3 packet will be dissected with skb->len in [65536, 65549]. Compare as u32 instead. If     the resulting offset cannot be represented in the u16 key_control->thoff, cap it to U16_MAX and report the     dissection as failed rather than silently returning a wrong transport offset. thoff is still set on     failure, as some callers (such as eth_get_headlen()) use it regardless of the return value.
    (CVE-2026-98955)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
381339	Ubuntu 26.04 LTS : Linux kernel vulnerabilities (USN-9018-1)	Nessus	Ubuntu Local Security Checks	Local	critical
379876	Amazon Linux 2 : kernel (ALASKERNEL-5.15-2026-121)	Nessus	Amazon Linux Local Security Checks	Local	critical
379844	Amazon Linux 2 : kernel (ALASKERNEL-5.10-2026-139)	Nessus	Amazon Linux Local Security Checks	Local	critical
375086	Photon OS 5.0: Linux PHSA-2026-5.0-92-1044	Nessus	PhotonOS Local Security Checks	Local	critical
373466	Amazon Linux 2023 : bpftool6.12, kernel6.12, kernel6.12-devel (ALAS2023-2026-3335)	Nessus	Amazon Linux Local Security Checks	Local	medium
371467	Linux Distros Unpatched Vulnerability : CVE-2026-98955	Nessus	Misc.	Local	medium

Detections

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CVE-2026-98955

high

Tenable Plugins

critical

critical

critical

critical

medium

medium