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VulnerabilityPublished Updated

CVE-2026-72380: Linux kernel · xen/pvcalls: bound backend response req_id before indexing rsp[]

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High · fixed in ede7a60b046d8b7288651c55198574ed7c259da7 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in ede7a60b046d8b7288651c55198574ed7c259da7, d33846c8dcc06b83b7acdeac1e8bfbb5c0c26cb2, d1297a9e2fd6ce08678b370d41bc980ca798f809 +2
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 2195046bfd69e487d9a76dc47840f15c8412840c, < ede7a60b046d8b7288651c55198574ed7c259da7
Fixed in
  • ede7a60b046d8b7288651c55198574ed7c259da7
LinuxLinuxAffected
  • ≥ 2195046bfd69e487d9a76dc47840f15c8412840c, < d33846c8dcc06b83b7acdeac1e8bfbb5c0c26cb2
Fixed in
  • d33846c8dcc06b83b7acdeac1e8bfbb5c0c26cb2
LinuxLinuxAffected
  • ≥ 2195046bfd69e487d9a76dc47840f15c8412840c, < d1297a9e2fd6ce08678b370d41bc980ca798f809
Fixed in
  • d1297a9e2fd6ce08678b370d41bc980ca798f809
LinuxLinuxAffected
  • ≥ 2195046bfd69e487d9a76dc47840f15c8412840c, < bc8f2d1c6f7cf6e6551c00eb582baf4b52a04794
Fixed in
  • bc8f2d1c6f7cf6e6551c00eb582baf4b52a04794
LinuxLinuxAffected
  • ≥ 2195046bfd69e487d9a76dc47840f15c8412840c, < 72e27ef70a20298e60a1de438f3628c515dea895
Fixed in
  • 72e27ef70a20298e60a1de438f3628c515dea895
LinuxLinuxAffected
  • =4.15
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: xen/pvcalls: bound backend response req_id before indexing rsp[] pvcalls_front_event_handler() takes req_id directly from the backend-supplied ring response and uses it to index the fixed-size bedata->rsp[] array for a memcpy() and a store, with no range check. A malicious or buggy backend can set req_id past PVCALLS_NR_RSP_PER_RING and drive an out-of-bounds write past the bedata allocation. req_id was also declared int while the wire field rsp->req_id is u32, so a range check on the signed value alone is insufficient: a backend req_id of 0xffffffff becomes -1, passes a >= PVCALLS_NR_RSP_PER_RING test and indexes bedata->rsp[-1]. Declare req_id as u32 so a single bound covers both ends. A backend that sends an out-of-range req_id has violated the wire protocol, so rather than silently dropping the response, log once and stop trusting the backend: set bedata->disabled. The event handler then ignores further responses, and the request paths that wait for a response return -EIO instead of blocking forever. This mirrors the fatal-error handling xen-netback uses (xenvif_fatal_tx_err()). The pvcalls frontend currently trusts its backend, so this is not a classic-Xen security issue, but it matters for hardening PV frontends against malicious backends (confidential and disaggregated deployments).

References

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