VulnerabilityPublished 18 Oct 2026

CVE-2026-98556: Linux kernel · gve: DQO: reject TSO packets with an out of range MSS

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in c517e8755960c8c6335ebf7dae6c95c43e5fb085 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c517e8755960c8c6335ebf7dae6c95c43e5fb085, 296c83b5ccc808c080865eb20fd7a477b0355bb7, 2dc3ae3942e151fef254b7bbb65c832192ad2069

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to c517e8755960c8c6335ebf7dae6c95c43e5fb085, 296c83b5ccc808c080865eb20fd7a477b0355bb7 or 2dc3ae3942e151fef254b7bbb65c832192ad2069.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a57e5de476be0b4b7f42beb6a21c19ad9c577aa3, < c517e8755960c8c6335ebf7dae6c95c43e5fb085	Fixed in c517e8755960c8c6335ebf7dae6c95c43e5fb085
LinuxLinux	Affected ≥ a57e5de476be0b4b7f42beb6a21c19ad9c577aa3, < 296c83b5ccc808c080865eb20fd7a477b0355bb7	Fixed in 296c83b5ccc808c080865eb20fd7a477b0355bb7
LinuxLinux	Affected ≥ a57e5de476be0b4b7f42beb6a21c19ad9c577aa3, < 2dc3ae3942e151fef254b7bbb65c832192ad2069	Fixed in 2dc3ae3942e151fef254b7bbb65c832192ad2069
LinuxLinux	Affected =5.14	Fixed in–

AI-suggested

A fix is available and has been applied to the Linux kernel. The patch drops TSO packets with an out-of-range MSS in gve_prep_tso() and adjusts feature checks to prevent oversized MSS values from being used. Users should update to the fixed kernel versions containing the patches identified by commits c517e8755960c8c6335ebf7dae6c95c43e5fb085, 296c83b5ccc808c080865eb20fd7a477b0355bb7, and 2dc3ae3942e151fef254b7bbb65c832192ad2069.

Description

A vulnerability in the Linux kernel's gve driver allows packets with an out-of-range Maximum Segment Size (MSS) to be processed incorrectly. The device requires MSS to be at most 9728 bytes, but this limit was not enforced for certain packets, allowing an attacker to craft packets with larger MSS values that cause the MSS field to wrap to zero. This issue arises because the MTU check is skipped for Generic Segmentation Offload (GSO) packets in the forwarding path. The vulnerability has been fixed by dropping such packets and adjusting feature checks to prevent oversized MSS values from being used.

Impact

Packets with an out-of-range MSS can bypass the intended MSS limit, causing the MSS field to wrap to zero, which may lead to incorrect handling of TSO packets by the gve device driver. This could potentially disrupt network packet processing or cause unexpected behavior in the network stack. The vulnerability affects scenarios where packets are not locally generated, such as guests behind taps or packet socket users, allowing them to send malformed packets that the driver mishandles.

Summary

The Linux kernel's gve driver did not enforce the MSS limit of 9728 bytes for TSO packets, assuming the hypervisor-enforced 9K MTU and 64KB TSO size limits were sufficient. However, packets not generated locally, such as those from guests behind a tap or packet socket users, could specify arbitrary gso_size values in virtio_net_hdr. The gso_size could exceed the 14-bit MSS field in the TSO context descriptor, causing MSS to wrap to zero. This could lead to incorrect packet processing. The fix involves dropping packets with out-of-range MSS in gve_prep_tso() and ensuring gve_features_check_dqo() does not alter GSO bits improperly, preventing oversized TSO packets from being passed to the device.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 10:38 UTC

Technical details

References

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