CVE-2024-50043
Description
A flaw was found in the Linux kernel's nfsd component. When multiple FREE_STATEIDs are sent for the same delegation stateid, a race condition can occur in the nfsd4_free_stateid() function. This allows the stateid to be accessed again after it has been prematurely released, leading to a use-after-free condition or a counter refcount underflow. This memory corruption vulnerability can result in system instability or a denial of service (DoS).
Mitigation
To mitigate this vulnerability, restrict network access to the NFS service to only trusted clients or networks. This can be achieved by configuring firewall rules.
For systems using `firewalld`:
`firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<TRUSTED_NETWORK>" port port="2049" protocol="tcp" accept'`
`firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<TRUSTED_NETWORK>" port port="2049" protocol="udp" accept'`
`firewall-cmd --reload`
Replace `<TRUSTED_NETWORK>` with the IP address or network range of your trusted NFS clients. This action may impact legitimate NFS clients if not configured correctly. Reloading the firewall service is required for changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | 7.8 | 9.8 |
| Attack Vector | Local | Local | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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