Is there a patch available for CVE-2026-98393?

Yes, a patch is available for CVE-2026-98393. Update the affected software to the latest version immediately.

Linux CVE-2026-98393

EUVD-2026-101042

2026-10-14 Linux

GHSA-m5wc-gf88-8h7m

Buffer Overflow Linux

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Monitor Track and reassess. Why: No CVSS yet + weak signal (CWE or non-zero EPSS).

Patch available 0.2% exploitation probability (EPSS)

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AnalysisCVE.org

In the Linux kernel, the following vulnerability has been resolved:

net: ipv4: Fix UDP length overflow with PMTU discover and big MTU

This commit bounds cork->base.fragsize to IP_MAX_MTU to avoid a possible overflow of UDP length that triggers a WARN in udp_set_len_short when setsockopt IP_MTU_DISCOVER is set to IP_PMTUDISC_PROBE, and a large packet is sent over a netdev with an unusually large MTU.

Steps to reproduce:

Set device MTU bigger than IP_MAX_MTU + 20. cork->base.fragsize will

be set to that MTU in ip_setup_cork.

Set IP_MTU_DISCOVER to IP_PMTUDISC_PROBE. It lets maxnonfragsize be

set to device MTU (cork->fragsize) in __ip_append_data, rather than to IP_MAX_MTU.

Send 65528 bytes of payload (+8 bytes of UDP header, +20 bytes of

IPv4 header). Device MTU allows it (it's only one byte bigger than IP_MAX_MTU + IPv4 header, and the device MTU is bigger than that).

The UDP length in the built packet is 65536, which overflows the

16-bit length field and triggers the WARN in udp_set_len_short.

Note: IP_PMTUDISC_DO with IPv4 is safe, because ip_dst_mtu_maybe_forward always clamps at IP_MAX_MTU, unlike ip6_dst_mtu_maybe_forward.

The Fixes tag points at the first commit where I could reproduce the overflow with IPv4 and IP_PMTUDISC_PROBE.

Affected VersionsENISA

Linux daba287b299ec7a2c61ae3a714920e90e8396ad5 <81f540827d243b8dad76c1f44e70ea31719f393c

Linux patch: 6.18.53

Linux patch: 7.2.7

Linux patch: 7.3-rc3

Linux patch: 0

Linux 3.13

Linux daba287b299ec7a2c61ae3a714920e90e8396ad5 <b83641e0ab8b20eefcc4cdc5a059f897375291a2

Linux daba287b299ec7a2c61ae3a714920e90e8396ad5 <83fedc4741210f75be8ca5b487985a242bf6f18d

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Exploit and PoC references, threat intelligence from 22 sources

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Lifecycle Timeline

Patch available

Oct 14, 2026 - 15:03 EUVD

CVE Published

Oct 14, 2026 - 13:25 cve.org

UNKNOWN (no severity yet)

Threat Intelligence Overview

EPSS Score

0.2%

Top 90% exploitable

Data Quality

3 sources

Confidence: Low

EUVD

CVE.org

EPSS MSRC

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity Not scored yet

CISA KEV No

Public POC No

EPSS 0.2%

Patch available Yes

Active threat No

Deciding rule

No CVSS yet + weak signal (CWE or non-zero EPSS)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.