Security readout for executives and security teams
Plain-English summary
A Linux kernel change can leak an internal reference when AFS-backed files are memory-mapped and a later merge or allocation fails. Repeated leakage may destabilize affected systems. The supplied CVSS score is 7.8, but the sources do not document observed attacks or a demonstrated impact beyond the reference leak.
Executive priority
Treat this as a high-priority kernel maintenance issue for systems using AFS, especially multi-user hosts. Accelerate inventory and vendor-supported updates, but avoid declaring an emergency solely from the score: active exploitation is not established, and the public description does not demonstrate the full scored confidentiality, integrity, and availability impact.
Technical view
Commit 9d5403b1036c converted AFS mmap handling to .mmap_prepare(). That callback increments a reference before later operations that may merge mappings or fail allocation, leaving the increment unreleased. The resolution reverts the AFS conversion while kernel support for safely using .mmap_prepare() in this situation is developed.
Likely exposure
Exposure is limited to Linux kernels containing the affected AFS change and reaching the AFS memory-mapping path. The supplied record lists releases including 6.17, 6.18.27, 7.0.4, and 7.1, but its version data is irregular. Confirm status against kernel or distribution advisories rather than relying solely on those labels.
Exploitation context
The CVSS vector describes a local, low-complexity attack requiring low privileges and no user interaction. The CVE is not listed as KEV, and the supplied sources provide no evidence of active exploitation, public exploitation, or a practical attack method.
Researcher notes
The documented defect is a reference-count leak caused by callback timing around VMA merging or allocation failure. No CWE is assigned. The supplied record does not quantify leak rate, reproducibility, reachable failure conditions, or how the leak produces the CVSS-scored confidentiality and integrity effects. Commit-level review and vendor backport mapping are necessary for precise exposure decisions.
Mitigation direction
- Install a vendor-supported kernel containing the applicable referenced stable fix.
- Prioritize systems using AFS or allowing untrusted local users.
- Follow distribution guidance where packaged kernel versions obscure upstream commit lineage.
- Restrict unnecessary local access while affected systems await an approved update.
Validation and detection
- Record each system's kernel release, distribution package, and build identifier.
- Check whether the kernel contains introducing commit 9d5403b1036c.
- Verify inclusion of the applicable referenced stable fix or vendor backport.
- Identify systems using AFS-backed file mappings and prioritize their remediation.
- Recheck vendor advisories because the supplied affected-version list is 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-2026-46100 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9LinuxVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/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/f51f85c044809fbd39ac8ae07ac99bc43ce32bd5CVE reference, Linux
- https://git.kernel.org/stable/c/48c7a0eaeea41da17d1d84d2d7a4c40be122b246CVE reference, Linux
- https://git.kernel.org/stable/c/fbfc6578eaca12daa0c09df1e9ba7f2c657b49daCVE 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.