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VulnerabilityPublished Updated

CVE-2026-46253: Linux kernel · pstore/ram: fix buffer overflow in persistent_ram_save_old()

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in cff0ef043e16feb5a02307c8f9d0117a96c5587c : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:07 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in cff0ef043e16feb5a02307c8f9d0117a96c5587c, 5669645c052f235726a85f443769b6fc02f66762, 58bda5a1d1ee98254383ef34f76b2c35140513ea +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 201e4aca5aa179e6c69a4dcd36a3562e56b8d670, < cff0ef043e16feb5a02307c8f9d0117a96c5587c
Fixed in
  • cff0ef043e16feb5a02307c8f9d0117a96c5587c
LinuxLinuxAffected
  • ≥ 201e4aca5aa179e6c69a4dcd36a3562e56b8d670, < 5669645c052f235726a85f443769b6fc02f66762
Fixed in
  • 5669645c052f235726a85f443769b6fc02f66762
LinuxLinuxAffected
  • ≥ 201e4aca5aa179e6c69a4dcd36a3562e56b8d670, < 58bda5a1d1ee98254383ef34f76b2c35140513ea
Fixed in
  • 58bda5a1d1ee98254383ef34f76b2c35140513ea
LinuxLinuxAffected
  • ≥ 201e4aca5aa179e6c69a4dcd36a3562e56b8d670, < 9a6fc69a570c0780834246d52c856cc3dbc2605f
Fixed in
  • 9a6fc69a570c0780834246d52c856cc3dbc2605f
LinuxLinuxAffected
  • ≥ 201e4aca5aa179e6c69a4dcd36a3562e56b8d670, < 7cfe964e61c0ab667abd5f5b68e0acbf783efa4f
Fixed in
  • 7cfe964e61c0ab667abd5f5b68e0acbf783efa4f
LinuxLinuxAffected
  • ≥ 201e4aca5aa179e6c69a4dcd36a3562e56b8d670, < 06d2c8bd108cea503f6f6e13e47495ed1085275f
Fixed in
  • 06d2c8bd108cea503f6f6e13e47495ed1085275f

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.

References

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