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CVE-2025-21655 (GCVE-0-2025-21655)

Vulnerability from cvelistv5 – Published: 2025-01-20 13:48 – Updated: 2026-09-08 08:40
VLAI
Title
io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period. Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < 6b63308c28987c6010b1180c72a6db4df6c68033 (git)
Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < 8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10 (git)
Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7 (git)
Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < c9a40292a44e78f71258b8522655bffaf5753bdb (git)
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Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 6.1.125 , ≤ 6.1.* (semver)
Unaffected: 6.6.72 , ≤ 6.6.* (semver)
Unaffected: 6.12.10 , ≤ 6.12.* (semver)
Unaffected: 6.13 , ≤ * (original_commit_for_fix)
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Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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      "status": "final",
      "title": "kernel: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-21655.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-16T00:19:16Z",
      "cve": "CVE-2025-21655",
      "id": "CVE-2025-21655",
      "initial_release_date": "2025-01-21T03:47:54Z",
      "product_status:known_affected": "410",
      "product_status:known_not_affected": "428",
      "product_status:recommended": "400",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-21655",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-21655.json",
      "version": "66"
    }
  }
}



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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.