VulnerabilityPublished 27 Dec 2024Updated 3 Nov 2025

CVE-2024-56633: Linux kernel · tcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg

Source GCVE Database

Compare

Not known to be exploited · CVSS 7.8 High.

Data as of 30 Oct 2026, 00:51 UTC

CVSS 3.1 base score

7.8High

How severe the flaw is on the 0–10 CVSS scale.

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Dec 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-gchp-wf2c-v3qv

What to do

AI-suggested

A fix for this vulnerability is available in the Linux kernel as described in the advisory. Users and administrators should update to the fixed kernel version that includes the corrected sk_mem_uncharge logic in tcp_bpf_sendmsg. No additional mitigation steps are indicated beyond applying the official patch.

Description

CVE-2024-56633 addresses a flaw in the Linux kernel's tcp_bpf_sendmsg function related to incorrect memory accounting (sk_mem_uncharge) during TCP message sending with BPF. The issue involves improper handling of socket memory charges when the number of bytes sent is less than expected, potentially leading to memory accounting inconsistencies and kernel warnings. The vulnerability was identified through kernel self-tests that triggered warnings related to socket destruction. The fix involves delaying the uncharging of memory until the actual sent bytes are finalized, ensuring accurate memory accounting.

Impact

The vulnerability can cause incorrect socket memory accounting in the Linux kernel, potentially leading to kernel warnings and instability related to socket destruction. The CVSS score of 7.8 (high severity) indicates that this flaw could impact confidentiality, integrity, and availability of the affected system due to improper resource management. However, there is no indication of active exploitation in the wild or direct remote attack vectors; the attack vector is local (AV:L) with low complexity and requires low privileges.

Summary

This vulnerability in the Linux kernel concerns the sk_mem_uncharge logic within the tcp_bpf_sendmsg function, specifically in the __SK_REDIRECT and __SK_DROP cases. The existing logic prematurely uncharges memory for bytes intended to be sent (tosend), which can lead to missed uncharging of bytes if the actual sent bytes are fewer than tosend, especially when tosend is adjusted to a smaller apply_bytes value and the send operation fails (ret < 0). This can cause memory accounting inconsistencies and kernel warnings during socket destruction, as observed in the selftest test_txmsg_redir_wait_sndmem with txmsg_apply. The patch corrects this by delaying the uncharging until after the actual sent bytes are determined, and properly freeing message buffers when send operations fail.

References

Community reviews

Loading reviews…