VulnerabilityPublished 23 Oct 2026

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

Source GCVE Database

Authoritative record:CVE-2026-99055· High

Not known to be exploited · fixed in 563d3564513496b9ce3b3ba7a5154427554d0f06 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 563d3564513496b9ce3b3ba7a5154427554d0f06, 8b1f0af1fd5fd113432233ed8a3862ee7c30a84f, 3aa6f536a95eb0617c313ae2eb76fdfa85331f85 +1

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.

ghsa-7h6j-x293-w79r

What to do

Upgrade Linux kernel to 563d3564513496b9ce3b3ba7a5154427554d0f06, 8b1f0af1fd5fd113432233ed8a3862ee7c30a84f, 3aa6f536a95eb0617c313ae2eb76fdfa85331f85 or 1c7463ac0e99cc91c4eecc1b69a740ef1a619932.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 9f6b619edf2e85746f261b42ae8f818a59d126f7, < 563d3564513496b9ce3b3ba7a5154427554d0f06	Fixed in 563d3564513496b9ce3b3ba7a5154427554d0f06
LinuxLinux	Affected ≥ 9f6b619edf2e85746f261b42ae8f818a59d126f7, < 8b1f0af1fd5fd113432233ed8a3862ee7c30a84f	Fixed in 8b1f0af1fd5fd113432233ed8a3862ee7c30a84f
LinuxLinux	Affected ≥ 9f6b619edf2e85746f261b42ae8f818a59d126f7, < 3aa6f536a95eb0617c313ae2eb76fdfa85331f85	Fixed in 3aa6f536a95eb0617c313ae2eb76fdfa85331f85
LinuxLinux	Affected ≥ 9f6b619edf2e85746f261b42ae8f818a59d126f7, < 1c7463ac0e99cc91c4eecc1b69a740ef1a619932	Fixed in 1c7463ac0e99cc91c4eecc1b69a740ef1a619932
LinuxLinux	Affected =6.12	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: tcp: reject net_iov in zerocopy receive mapping hints After copying a readable prefix, receive_fallback_to_copy() asks tcp_zerocopy_set_hint_for_skb() where page mapping can resume. If the next skb is unreadable, find_next_mappable_frag() passes its net_iov fragment to can_map_frag(). skb_frag_page() returns NULL for a net_iov, but can_map_frag() dereferences it in PageCompound(). A v7.2 KASAN run on a connected TCP socket with 64 readable bytes followed by a 4096-byte NET_IOV_DMABUF fragment reported: BUG: KASAN: null-ptr-deref in can_map_frag tcp_zerocopy_receive -> can_map_frag Kernel panic - not syncing: KASAN: panic_on_warn set The diagnostic inserted the net_iov directly because the test host has no devmem-capable NIC. Hardware end-to-end reachability remains untested and requires CONFIG_NET_DEVMEM plus a supported DMA-buf-bound RX queue. Reject all net_iov fragments before skb_frag_page(). This covers both DMABUF and IOURING net_iov types while leaving page-backed checks unchanged. With the guard, the same queue copied the readable prefix, returned a 4096-byte skip hint, and completed without a fault.

References

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