VulnerabilityPublished 26 Oct 2026Updated 27 Oct 2026

CVE-2026-99055: Linux kernel · tcp: reject net_iov in zerocopy receive mapping hints

Affects Linux kernelSource GCVE Database

Authoritative record:CVE-2026-99055· High

Not known to be exploited.

Data as of 28 Oct 2026, 01:43 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

Exploitation evidence

Disclosed: evidence found.
CVE published 23 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

Affected software

Product	Affected	Fixed in
Ubuntu 26.10linux`pkg:deb/ubuntu/linux?arch=source&distro=stonking`Other threats	Affected 7.0.0-14.14 – 7.3.0-9.9 6 affected builds	Fixed in–
Ubuntu 26.10linux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=stonking`Other threats	Affected 7.0.0-1004.4 – 7.3.0-1003.3 5 affected builds	Fixed in–
Ubuntu 26.10linux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=stonking`Other threats	Affected 7.0.0-1004.4 – 7.3.0-1003.3 5 affected builds	Fixed in–
Ubuntu 26.10linux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=stonking`Other threats	Affected =7.0.0-1004.4 =7.3.0-1002.3 =7.3.0-1003.4	Fixed in–
Ubuntu 26.10linux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=stonking`Other threats	Affected 7.0.0-1003.3 – 7.3.0-1003.3 5 affected builds	Fixed in–
Ubuntu 26.10linux-oracle`pkg:deb/ubuntu/linux-oracle?arch=source&distro=stonking`Other threats	Affected 7.0.0-1003.3 – 7.3.0-1003.3 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available that rejects all net_iov fragments before skb_frag_page() is called, preventing the null pointer dereference. Users should apply the updated Linux kernel versions that include this fix. No additional mitigation steps are indicated.

Description

A vulnerability in the Linux kernel TCP zerocopy receive path could cause a kernel panic due to a null pointer dereference when processing net_iov fragments. This occurs because the code incorrectly dereferences a NULL page pointer for net_iov fragments, leading to a KASAN-detected panic. The issue has been resolved by rejecting all net_iov fragments before accessing page-backed data, preventing the fault.

Impact

Exploitation of this vulnerability can cause a kernel panic due to a null pointer dereference in the TCP zerocopy receive path. This results in denial of service on affected systems. There is no indication of code execution or privilege escalation. The issue was detected by KASAN during testing and may require specific hardware configurations to reproduce.

Summary

The Linux kernel TCP zerocopy receive implementation improperly handles net_iov fragments in the receive mapping hints. After copying a readable prefix, the function receive_fallback_to_copy() calls tcp_zerocopy_set_hint_for_skb() to resume page mapping. If the next socket buffer (skb) fragment is unreadable and is a net_iov type, skb_frag_page() returns NULL, but can_map_frag() dereferences this NULL pointer in PageCompound(), causing a kernel panic detected by KASAN. The fix rejects all net_iov fragments before skb_frag_page() is called, covering both DMABUF and IOURING net_iov types, thus preventing the null pointer dereference and kernel panic.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Oct 2026, 01:43 UTC

Technical details

References

Community reviews

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