CyberSecBulletin
CVE-2025-38488NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2025-38488 is a high-severity use after free 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 5d047b12f86cc3b9fde1171c02d9bccf4dba0632, 6550b2bef095d0dd2d2c8390d2ea4c3837028833, 9a1d3e8d40f151c2d5a5f40c410e6e433f62f438 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 0.77% chance of exploitation within 30 days, higher than 56% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 5d047b12f86cc3b9fde1171c02d9bccf4dba0632 or 6550b2bef095d0dd2d2c8390d2ea4c3837028833 or 9a1d3e8d40f151c2d5a5f40c410e6e433f62f438 or 15a0a5de49507062bc3be4014a403d8cea5533de, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.241 or 5.15.190 or 6.1.147 or 6.6.100, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux8f14a476abba13144df5434871a7225fd29af633 up to, but not including, 5d047b12f86cc3b9fde1171c02d9bccf4dba0632; ef51c0d544b1518b35364480317ab6d3468f205d up to, but not including, 6550b2bef095d0dd2d2c8390d2ea4c3837028833; bce966530fd5542bbb422cb45ecb775f7a1a6bc3 up to, but not including, 9a1d3e8d40f151c2d5a5f40c410e6e433f62f438; 0809fb86ad13b29e1d6d491364fc7ea4fb545995 up to, but not including, 15a0a5de49507062bc3be4014a403d8cea5533de; b0abcd65ec545701b8793e12bc27dc98042b151a up to, but not including, 2a76bc2b24ed889a689fb1c9015307bf16aafb5b; b0abcd65ec545701b8793e12bc27dc98042b151a up to, but not including, 8ac90f6824fc44d2e55a82503ddfc95defb19ae0; b0abcd65ec545701b8793e12bc27dc98042b151a up to, but not including, b220bed63330c0e1733dc06ea8e75d5b9962b6b6; 538c26d9bf70c90edc460d18c81008a4e555925a; and 6 more ranges5d047b12f86cc3b9fde1171c02d9bccf4dba0632, 6550b2bef095d0dd2d2c8390d2ea4c3837028833, 9a1d3e8d40f151c2d5a5f40c410e6e433f62f438, 15a0a5de49507062bc3be4014a403d8cea5533de, 2a76bc2b24ed889a689fb1c9015307bf16aafb5b, 8ac90f6824fc44d2e55a82503ddfc95defb19ae0
LinuxLinux Kernel5.10.237 up to, but not including, 5.10.241; 5.15.181 up to, but not including, 5.15.190; 6.1.128 up to, but not including, 6.1.147; 6.6.57 up to, but not including, 6.6.100; 6.11.4 up to, but not including, 6.12.40; 6.13 up to, but not including, 6.15.8; 6.165.10.241, 5.15.190, 6.1.147, 6.6.100, 6.12.40, 6.15.8
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: smb: client: fix use-after-free in crypt_message when using async crypto The CVE-2024-50047 fix removed asynchronous crypto handling from crypt_message(), assuming all crypto operations are synchronous. However, when hardware crypto accelerators are used, this can cause use-after-free crashes: crypt_message() // Allocate the creq buffer containing the req creq = smb2_get_aead_req(..., &req); // Async encryption returns -EINPROGRESS immediately rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req); // Free creq while async operation is still in progress kvfree_sensitive(creq, ...); Hardware crypto modules often implement async AEAD operations for performance. When crypto_aead_encrypt/decrypt() returns -EINPROGRESS, the operation completes asynchronously. Without crypto_wait_req(), the function immediately frees the request buffer, leading to crashes when the driver later accesses the freed memory. This results in a use-after-free condition when the hardware crypto driver later accesses the freed request structure, leading to kernel crashes with NULL pointer dereferences. The issue occurs because crypto_alloc_aead() with mask=0 doesn't guarantee synchronous operation. Even without CRYPTO_ALG_ASYNC in the mask, async implementations can be selected. Fix by restoring the async crypto handling: - DECLARE_CRYPTO_WAIT(wait) for completion tracking - aead_request_set_callback() for async completion notification - crypto_wait_req() to wait for operation completion This ensures the request buffer isn't freed until the crypto operation completes, whether synchronous or asynchronous, while preserving the CVE-2024-50047 fix.

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

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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