Incorrect Conversion between Numeric Types Affecting kernel-rt-64k-debug package, versions *


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.17% (7th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-RHEL10-KERNELRT64KDEBUG-21795161
  • published29 Oct 2026
  • disclosed23 Oct 2026

Introduced: 23 Oct 2026

NewCVE-2026-98955  (opens in a new tab)
CWE-681  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:10 kernel-rt-64k-debug.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-debug package and not the kernel-rt-64k-debug package as distributed by RHEL. See How to fix? for RHEL:10 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1