What is the CVSS score of CVE-2024-26924?

CVE-2024-26924 has a CVSS 3.1 base score of 5.9 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 1.3%.

Is there a patch available for CVE-2024-26924?

Yes, a patch is available for CVE-2024-26924. Update the affected software to the latest version immediately.

Linux Kernel CVE-2024-26924

MEDIUM

NULL Pointer Dereference (CWE-476)

2024-04-25 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Null Pointer Dereference Denial Of Service Linux Linux Kernel Debian Linux

5.9

CVSS 3.1 · Vendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Severity by source

Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67) PRIMARY

5.9 MEDIUM

AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67) · only source for this CVE.

CVSS VectorVendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

CVE Published

Apr 25, 2024 - 06:15 cve.org

MEDIUM 5.9

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_set_pipapo: do not free live element

Pablo reports a crash with large batches of elements with a back-to-back add/remove pattern. Quoting Pablo:

add_elem("00000000") timeout 100 ms ... add_elem("0000000X") timeout 100 ms del_elem("0000000X") <---------------- delete one that was just added ... add_elem("00005000") timeout 100 ms

nft_pipapo_remove() removes element 0000000X

Then, KASAN shows a splat.

Looking at the remove function there is a chance that we will drop a rule that maps to a non-deactivated element.

Removal happens in two steps, first we do a lookup for key k and return the to-be-removed element and mark it as inactive in the next generation. Then, in a second step, the element gets removed from the set/map.

The _remove function does not work correctly if we have more than one element that share the same key.

This can happen if we insert an element into a set when the set already holds an element with same key, but the element mapping to the existing key has timed out or is not active in the next generation.

In such case its possible that removal will unmap the wrong element. If this happens, we will leak the non-deactivated element, it becomes unreachable.

The element that got deactivated (and will be freed later) will remain reachable in the set data structure, this can result in a crash when such an element is retrieved during lookup (stale pointer).

Add a check that the fully matching key does in fact map to the element that we have marked as inactive in the deactivation step. If not, we need to continue searching.

Add a bug/warn trap at the end of the function as well, the remove function must not ever be called with an invisible/unreachable/non-existent element.

v2: avoid uneeded temporary variable (Stefano)

AnalysisAI

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo: do not free live element Pablo reports a crash with large batches of elements with a back-to-back. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.

Technical ContextAI

This vulnerability is classified as NULL Pointer Dereference (CWE-476), which allows attackers to crash the application by dereferencing a null pointer. In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo: do not free live element Pablo reports a crash with large batches of elements with a back-to-back add/remove pattern. Quoting Pablo: add_elem("00000000") timeout 100 ms ... add_elem("0000000X") timeout 100 ms del_elem("0000000X") <---------------- delete one that was just added ... add_elem("00005000") timeout 100 ms 1) nft_pipapo_remove() removes element 0000000X Then, KASAN shows a splat. Looking at the remove function there is a chance that we will drop a rule that maps to a non-deactivated element. Removal happens in two steps, first we do a lookup for key k and return the to-be-removed element and mark it as inactive in the next generation. Then, in a second step, the element gets removed from the set/map. The _remove function does not work correctly if we have more than one element that share the same key. This can happen if we insert an element into a set when the set already holds an element with same key, but the element mapping to the existing key has timed out or is not active in the next generation. In such case its possible that removal will unmap the wrong element. If this happens, we will leak the non-deactivated element, it becomes unreachable. The element that got deactivated (and will be freed later) will remain reachable in the set data structure, this can result in a crash when such an element is retrieved during lookup (stale pointer). Add a check that the fully matching key does in fact map to the element that we have marked as inactive in the deactivation step. If not, we need to continue searching. Add a bug/warn trap at the end of the function as well, the remove function must not ever be called with an invisible/unreachable/non-existent element. v2: avoid uneeded temporary variable (Stefano) Affected products include: Linux Linux Kernel, Debian Debian Linux.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Check pointers before dereferencing. Use static analysis tools to detect null pointer paths.