Critical

CVE-2026-63922 — ipv6: exthdrs: refresh nh after handling HAO option

In the Linux kernel, the following vulnerability has been resolved: ipv6: exthdrs: refresh nh after handling HAO option ip6_parse_tlv() caches skb_network_header(skb) in nh while walking IPv6 TLVs. ipv6_dest_hao() may call pskb_expand_head() for a cloned skb, which can move the skb head and invalidate the cached network header pointer. Refresh nh after ipv6_dest_hao() returns so any trailing padding or TLVs are parsed from the current skb head. This matches the existing pattern used in ip6_parse_tlv() after helpers that can modify skb header storage.

Published Jul 19, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.7% (30-day exploitation probability)+8
Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.71%

ahead of 53% of scored CVEs · Oct 15, 2026

Affects

Linux

CVSS base

9.8

Critical · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < b3ac54e5c905f86d22b502eacb5686a282c5659f≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < f8aabed3ff3e986920cf02a2a2785e08e586b234≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < 1a11eb7431e3d2882f5bd5939c5a9bbc65ccf4d1≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < 12d957979e4a800167842f1b42be6a606d227ebe≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < ff375ed1cba81392346c5bfbf0bb7a13b2946f99≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < 751db1b802a067b7fff25880f4e9f9152a171538≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < 9b6dcc0a39fd71752937f0b6b3973e1416085dcf≥ a831f5bbc89a9978795504be9e1ff412043f8f77 and < f7b52afe3592eae66e160586b45a3f2242972c63 and 1 more version 2.6.19	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.8	CVSS 3.1	Critical	3.9	5.9	416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
9.8	CVSS 3.1	Critical	—	—	Linux via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 9.8
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Awaiting Analysis
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 19, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

git.kernel.org/stable/c/9b6dcc0a39fd71752937f0b6b3973e1416085dcf
NIST National Vulnerability Database
git.kernel.org/stable/c/b3ac54e5c905f86d22b502eacb5686a282c5659f
NIST National Vulnerability Database
git.kernel.org/stable/c/f8aabed3ff3e986920cf02a2a2785e08e586b234
NIST National Vulnerability Database
git.kernel.org/stable/c/f7b52afe3592eae66e160586b45a3f2242972c63
NIST National Vulnerability Database
git.kernel.org/stable/c/1a11eb7431e3d2882f5bd5939c5a9bbc65ccf4d1
NIST National Vulnerability Database
git.kernel.org/stable/c/751db1b802a067b7fff25880f4e9f9152a171538
NIST National Vulnerability Database
git.kernel.org/stable/c/12d957979e4a800167842f1b42be6a606d227ebe
NIST National Vulnerability Database
git.kernel.org/stable/c/ff375ed1cba81392346c5bfbf0bb7a13b2946f99
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 16h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 16h
Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d
Unknown CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-63922 is "ipv6: exthdrs: refresh nh after handling HAO option", rated Critical. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.71% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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