Security readout for executives and security teams
Plain-English summary
A Linux kernel iomap read-path bug can leave a folio referenced after the I/O helper has taken ownership, creating invalid memory access. It occurs when filesystem block size matches folio size but differs from I/O granularity. Impact could be severe, but supplied sources do not establish a practical remote attack path, affected filesystems, or exploitation in the wild.
Executive priority
Urgent verification and scheduled remediation are warranted because this is kernel memory-safety behavior with a supplied critical score. Escalate to emergency patching where an affected build and reachable iomap workload are confirmed. For other systems, obtain distributor guidance quickly; current evidence does not justify claiming widespread remote exploitation.
Technical view
During iomap_read_folio_iter(), partial-folio I/O in the no-ifs path may leave ctx->cur_folio set. iomap_read_end() can then act on a folio whose completion is owned by the I/O helper. The fix unconditionally clears ctx->cur_folio for that path. Supplied metadata identifies Linux 6.19-era releases as affected, but its flattened version bounds are ambiguous; confirm distributor mappings.
Likely exposure
Potentially exposed systems run affected Linux 6.19-series kernels and exercise the specific iomap read configuration. The bundle does not name distributions, filesystems, default configurations, cloud images, or appliances. It also contains unusual flattened version data around 6.19.11 and 7.0, so confirm package-level exposure with the relevant Linux distributor.
Exploitation context
KEV status is false, and no supplied source reports active exploitation, public proof-of-concept code, or a demonstrated remote attack chain. Although the supplied CVSS 9.8 vector indicates network-accessible, low-complexity, unauthenticated exploitation, the technical record does not explain how an external attacker reaches the faulty kernel path. Treat that gap as uncertainty, not proof of safety.
Researcher notes
The record describes a lifetime or ownership error in the no-ifs iomap read path, corrected by unconditional current-folio invalidation. No CWE, affected filesystem list, trigger provenance, crash signature, or exploit demonstration is supplied. The CVSS network vector is not reconciled with the code-level description, and version normalization is unclear; downstream advisories remain essential evidence.
Mitigation direction
- Inventory deployed Linux kernel versions, including distribution package and backport identifiers.
- Prioritize a supported kernel update containing the referenced fix; confirm the exact fixed build with your distributor.
- Reboot systems into the updated kernel and avoid continued operational use of vulnerable kernel builds.
- If updating is delayed, request vendor-supported mitigations; none are identified in the supplied sources.
Validation and detection
- Compare each running kernel's source or package changelog against the two referenced stable commits.
- Verify the no-ifs iomap path unconditionally clears ctx->cur_folio before read-end handling.
- Confirm whether affected workloads use iomap reads where block size and I/O granularity differ.
- Review kernel crash telemetry for iomap-related invalid folio access; absence of crashes does not establish non-exposure.
- Recheck distributor advisories because the supplied version bounds are ambiguous.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CVE-2026-31463 mapping review
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Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9LinuxVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/4a927f670cdb0def226f9f85f42a9f19d9e09c88CVE reference, Linux
- https://git.kernel.org/stable/c/bd71fb3fea9945987053968f028a948997cba8ccCVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.