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CVE Record

CVE-2021-47357: atm: iphase: fix possible use-after-free in ia_module_exit()

In the Linux kernel, the following vulnerability has been resolved: atm: iphase: fix possible use-after-free in ia_module_exit() This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel driver cleanup bug. When the iphase ATM driver is removed, a timer callback may still be running and touch memory that has already been freed. The source does not provide a CVSS score or evidence of active exploitation.

Executive priority

Treat this as a kernel maintenance issue with unknown severity and likely narrow exposure. It should be patched through normal kernel update cycles, faster where legacy ATM hardware or custom kernel modules are in use.

Technical view

CVE-2021-47357 affects the Linux kernel atm iphase driver. The module exit path used del_timer(), which does not wait for an active timer handler to finish. The resolved fix changes the removal path to del_timer_sync() so the handler has completed and cannot reschedule itself before resources are freed.

Likely exposure

Exposure appears limited to Linux systems with affected kernel versions where the iphase ATM driver is present and can be loaded or removed. The source bundle does not provide CPEs, distribution package names, or confirmed affected downstream vendor builds.

Exploitation context

The bundle marks KEV as false and provides no cited evidence of active exploitation or a public exploit. The described failure condition is a driver removal race involving a timer handler, but practical exploitation requirements are not established in the provided sources.

Researcher notes

The source identifies a use-after-free risk in ia_module_exit() caused by asynchronous timer deletion. The published affected data is broad and commit-oriented, with no CVSS, CWE, exploit evidence, or downstream vendor mapping included.

Mitigation direction

  • Apply Linux kernel or distribution updates containing the referenced stable fixes.
  • Check your Linux vendor advisory for affected package versions and backported fixes.
  • Remove or avoid loading the iphase ATM driver where it is not required.
  • Prioritize systems using ATM hardware or custom kernels with this driver enabled.

Validation and detection

  • Inventory kernel versions against vendor guidance for CVE-2021-47357.
  • Confirm whether the iphase ATM driver is built, loadable, or actively used.
  • Verify deployed kernels include the stable fix changing del_timer() to del_timer_sync().
  • Review kernel logs for related driver removal instability if the driver is used.
Prepared
Confidence
medium
Sources
11

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-47357 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
3Timeline events
2ADP providers
10Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2unaffected
LinuxLinux2.6.12, 0, 4.4.276, 4.9.276, 4.14.240, 4.19.198, 5.4.133, 5.10.51, 5.12.18, 5.13.3, 5.14affected
Weakness

CWE details

No CWE listed

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