CyberSecBulletin
CVE-2026-46253NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-46253 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 58bda5a1d1ee98254383ef34f76b2c35140513ea, 06d2c8bd108cea503f6f6e13e47495ed1085275f, 2fa9a047c6a50ec80c3890dd623b85e237f0d1fd 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 0.17% 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 58bda5a1d1ee98254383ef34f76b2c35140513ea or 06d2c8bd108cea503f6f6e13e47495ed1085275f or 2fa9a047c6a50ec80c3890dd623b85e237f0d1fd or cff0ef043e16feb5a02307c8f9d0117a96c5587c, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.252 or 5.15.202 or 6.1.165 or 6.6.128, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 58bda5a1d1ee98254383ef34f76b2c35140513ea; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 06d2c8bd108cea503f6f6e13e47495ed1085275f; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 2fa9a047c6a50ec80c3890dd623b85e237f0d1fd; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, cff0ef043e16feb5a02307c8f9d0117a96c5587c; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 9a6fc69a570c0780834246d52c856cc3dbc2605f; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 4f73486ca822305c1cf5b8ebc0b53a6ab3801a81; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 7cfe964e61c0ab667abd5f5b68e0acbf783efa4f; 201e4aca5aa179e6c69a4dcd36a3562e56b8d670 up to, but not including, 5669645c052f235726a85f443769b6fc02f66762; and 1 more ranges58bda5a1d1ee98254383ef34f76b2c35140513ea, 06d2c8bd108cea503f6f6e13e47495ed1085275f, 2fa9a047c6a50ec80c3890dd623b85e237f0d1fd, cff0ef043e16feb5a02307c8f9d0117a96c5587c, 9a6fc69a570c0780834246d52c856cc3dbc2605f, 4f73486ca822305c1cf5b8ebc0b53a6ab3801a81
LinuxLinux Kernel3.5.1 up to, but not including, 5.10.252; 5.11 up to, but not including, 5.15.202; 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.14; 6.19 up to, but not including, 6.19.4; 3.55.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: pstore/ram: fix buffer overflow in persistent_ram_save_old() persistent_ram_save_old() can be called multiple times for the same persistent_ram_zone (e.g., via ramoops_pstore_read -> ramoops_get_next_prz for PSTORE_TYPE_DMESG records). Currently, the function only allocates prz->old_log when it is NULL, but it unconditionally updates prz->old_log_size to the current buffer size and then performs memcpy_fromio() using this new size. If the buffer size has grown since the first allocation (which can happen across different kernel boot cycles), this leads to: 1. A heap buffer overflow (OOB write) in the memcpy_fromio() calls 2. A subsequent OOB read when ramoops_pstore_read() accesses the buffer using the incorrect (larger) old_log_size The KASAN splat would look similar to: BUG: KASAN: slab-out-of-bounds in ramoops_pstore_read+0x... Read of size N at addr ... by task ... The conditions are likely extremely hard to hit: 0. Crash with a ramoops write of less-than-record-max-size bytes. 1. Reboot: ramoops registers, pstore_get_records(0) reads old crash, allocates old_log with size X 2. Crash handler registered, timer started (if pstore_update_ms >= 0) 3. Oops happens (non-fatal, system continues) 4. pstore_dump() writes oops via ramoops_pstore_write() size Y (>X) 5. pstore_new_entry = 1, pstore_timer_kick() called 6. System continues running (not a panic oops) 7. Timer fires after pstore_update_ms milliseconds 8. pstore_timefunc() → schedule_work() → pstore_dowork() → pstore_get_records(1) 9. ramoops_get_next_prz() → persistent_ram_save_old() 10. buffer_size() returns Y, but old_log is X bytes 11. Y > X: memcpy_fromio() overflows heap Requirements: - a prior crash record exists that did not fill the record size (almost impossible since the crash handler writes as much as it can possibly fit into the record, capped by max record size and the kmsg buffer almost always exceeds the max record size) - pstore_update_ms >= 0 (disabled by default) - Non-fatal oops (system survives) Free and reallocate the buffer when the new size differs from the previously allocated size. This ensures old_log always has sufficient space for the data being copied.

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

Recent Out-of-bounds Write vulnerabilities

Spotted an error? Tell us.