CVE-2026-64132: In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: refresh hdr pointer before ioam6_event() Reported by Sashiko: In ip...

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: refresh hdr pointer before ioam6_event() Reported by Sashiko: In ipv6_hop_ioam(), the hdr pointer is initialized to point into the skb's linear data buffer. Later, the code calls skb_ensure_writable(), which might reallocate the buffer: if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len)) goto drop; /* Trace pointer may have changed */ trace = (struct ioam6_trace_hdr *)(skb_network_header(skb) + optoff + sizeof(*hdr)); ioam6_fill_trace_data(skb, ns, trace, true); ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev), GFP_ATOMIC, (void *)trace, hdr->opt_len - 2); If the skb is cloned or lacks sufficient linear headroom, skb_ensure_writable() will invoke pskb_expand_head(), which reallocates the skb's data buffer and frees the old one, invalidating pointers to it. While the code recalculates the trace pointer immediately after the call to skb_ensure_writable(), it fails to recalculate the hdr pointer. This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.49%

39.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= f655c78d6225f585ef60a9d93ffb79d507ff3ad3, < 769723124b7c3b2bfea4cf68ad292698b87c8d01; >= f655c78d6225f585ef60a9d93ffb79d507ff3ad3, < 24de676da63c1122d2c13b0d546238b66d1b4e62; >= f655c78d6225f585ef60a9d93ffb79d507ff3ad3, < 5af905aa8e91ff8d94572a1e089558f21dcf24ed; >= f655c78d6225f585ef60a9d93ffb79d507ff3ad3, < e46e6bc97fb1f339730ff1ba74267fbf48e7a422
Linux	Linux	6.9

References

Timeline

Published: Jul 19, 2026
Last Modified: Jul 30, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-64132?

In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: refresh hdr pointer before ioam6_event() Reported by Sashiko: In ipv6_hop_ioam(), the hdr pointer is initialized to point into the skb's linear data buffer. Later, the code calls skb_ensure_writable(), which might reallocate the buffer: if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len)) goto drop; /* Trace pointer may have changed */ trace = (struct ioam6_trace_hdr *)(skb_network_header(skb) + optoff + sizeof(*hdr)); ioam6_fill_trace_data(skb, ns, trace, true); ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev), GFP_ATOMIC, (void *)trace, hdr->opt_len - 2); If the skb is cloned or lacks sufficient linear headroom, skb_ensure_writable() will invoke pskb_expand_head(), which reallocates the skb's data buffer and frees the old one, invalidating pointers to it. While the code recalculates the trace pointer immediately after the call to skb_ensure_writable(), it fails to recalculate the hdr pointer. This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.

How severe is CVE-2026-64132?

CVE-2026-64132 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.49% probability of exploitation in the next 30 days.

How do I fix CVE-2026-64132?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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