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CVE-2026-53165 Linux CVE debrief

A vulnerability in the Linux kernel has been resolved, which could lead to a null pointer dereference during error reporting. The vulnerability occurs when a buffered read fails, and the error is reported with fserror_report_io(). This function is called after ifs->read_bytes_pending has been decremented by the bytes attempted to be read. For a folio split across multiple read completions, the folio is only guaranteed to stay locked while read_bytes_pending > 0. Once iomap_finish_folio_read() decrements read_bytes_pending, another in-flight read can complete and end the read on the folio, which unlocks it. This allows truncate logic to run and detach the folio (set folio->mapping to NULL). The error reporting path then can dereference a NULL folio->mapping.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-25
Original CVE updated
2026-06-28
Advisory published
2026-06-25
Advisory updated
2026-06-28

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take necessary actions to protect their systems. The vulnerability has a CVSS score of 7.5 and a HIGH severity rating. Users of Linux kernel versions that are affected by this vulnerability should apply the necessary patches to prevent exploitation.

Technical summary

The vulnerability occurs in the iomap_finish_folio_read() function, which reports errors with fserror_report_io(). The function is called after ifs->read_bytes_pending has been decremented, which can lead to a null pointer dereference if the folio is detached by truncate logic. The vulnerability can be exploited by an attacker to cause a denial-of-service (DoS) or potentially execute arbitrary code.

Defensive priority

High priority should be given to applying patches to fix this vulnerability. Linux kernel users and administrators should monitor their systems for any suspicious activity and apply the necessary patches as soon as possible.

Recommended defensive actions

  • Apply the necessary patches to fix the vulnerability
  • Monitor systems for suspicious activity
  • Review and update Linux kernel configurations to prevent exploitation
  • Implement compensating controls to detect and prevent similar vulnerabilities
  • Perform regular vulnerability scans and penetration testing to identify potential weaknesses

Evidence notes

The vulnerability was reported by Sam Sun and was resolved by reporting the error first before decrementing ifs->read_bytes_pending. The CVE record and NVD detail provide additional information about the vulnerability.

Official resources

This article was generated with AI assistance and is based on the supplied source corpus.