CyberSecBulletin
CVE-2025-39841NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2025-39841 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions ab34084f42ee06a9028d67c78feafb911d33d111, baa39f6ad79d372a6ce0aa639fbb2f1578479f57, 95b63d15fce5c54a73bbf195e1aacb5a75b128e2 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to ab34084f42ee06a9028d67c78feafb911d33d111 or baa39f6ad79d372a6ce0aa639fbb2f1578479f57 or 95b63d15fce5c54a73bbf195e1aacb5a75b128e2 or 55658c7501467ca9ef3bd4453dd920010db8bc13, whichever matches your release line, or a later version.
  2. Update RUGGEDCOM RST2428P to V3.3 or a later version.
  3. Update SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family to V3.3 or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, ab34084f42ee06a9028d67c78feafb911d33d111; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, baa39f6ad79d372a6ce0aa639fbb2f1578479f57; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, 95b63d15fce5c54a73bbf195e1aacb5a75b128e2; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, 55658c7501467ca9ef3bd4453dd920010db8bc13; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, d96cc9a1b57725930c60b607423759d563b4d900; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, 367cb5ffd8a8a4c85dc89f55e7fa7cc191425b11; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, 897f64b01c1249ac730329b83f4f40bab71e86c7; 472e146d1cf3410a898b49834500fa9e33ac41a2 up to, but not including, 9dba9a45c348e8460da97c450cddf70b2056deb3; and 1 more rangesab34084f42ee06a9028d67c78feafb911d33d111, baa39f6ad79d372a6ce0aa639fbb2f1578479f57, 95b63d15fce5c54a73bbf195e1aacb5a75b128e2, 55658c7501467ca9ef3bd4453dd920010db8bc13, d96cc9a1b57725930c60b607423759d563b4d900, 367cb5ffd8a8a4c85dc89f55e7fa7cc191425b11
SiemensRUGGEDCOM RST2428Pbefore V3.3V3.3
SiemensSCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 familybefore V3.3V3.3
SiemensSCALANCE XCH328before V3.3V3.3
SiemensSCALANCE XCM324before V3.3V3.3
SiemensSCALANCE XCM328before V3.3V3.3
SiemensSCALANCE XCM332before V3.3V3.3
SiemensSCALANCE XRH334 (24 V DC, 8xFO, CC)before V3.3V3.3
SiemensSCALANCE XRM334 (230 V AC, 12xFO)before V3.3V3.3
SiemensSCALANCE XRM334 (230 V AC, 8xFO)before V3.3V3.3
SiemensSCALANCE XRM334 (230V AC, 2x10G, 24xSFP, 8xSFP+)before V3.3V3.3
SiemensSCALANCE XRM334 (24 V DC, 12xFO)before V3.3V3.3
SiemensSCALANCE XRM334 (24 V DC, 8xFO)before V3.3V3.3
SiemensSCALANCE XRM334 (24V DC, 2x10G, 24xSFP, 8xSFP+)before V3.3V3.3
SiemensSCALANCE XRM334 (2x230 V AC, 12xFO)before V3.3V3.3
SiemensSCALANCE XRM334 (2x230 V AC, 8xFO)before V3.3V3.3
SiemensSCALANCE XRM334 (2x230V AC, 2x10G, 24xSFP, 8xSFP+)before V3.3V3.3
SiemensSIMATIC CN 4100before V5.0V5.0
LinuxLinux Kernel5.1 up to, but not including, 5.4.299; 5.5 up to, but not including, 5.10.243; 5.11 up to, but not including, 5.15.192; 5.16 up to, but not including, 6.1.151; 6.2 up to, but not including, 6.6.105; 6.7 up to, but not including, 6.12.46; 6.13 up to, but not including, 6.16.6; 6.175.4.299, 5.10.243, 5.15.192, 6.1.151, 6.6.105, 6.12.46
DebianDebian Linux11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix buffer free/clear order in deferred receive path Fix a use-after-free window by correcting the buffer release sequence in the deferred receive path. The code freed the RQ buffer first and only then cleared the context pointer under the lock. Concurrent paths (e.g., ABTS and the repost path) also inspect and release the same pointer under the lock, so the old order could lead to double-free/UAF. Note that the repost path already uses the correct pattern: detach the pointer under the lock, then free it after dropping the lock. The deferred path should do the same.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Out-of-bounds Write vulnerabilities

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