Critical severity · published Oct 23, 2026
CVE-2026-99078
net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
New
9.8
CVSS
0.5%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
With AF_XDP on a striding RQ, mlx5e defers releasing XSK buffers until
an MPWQE is refilled. If XSK allocation then returns -ENOMEM,
actual_wq_head is not advanced and a later NAPI poll retries the same
WQE.
mlx5e_free_rx_mpwqe() leaves each released slot marked as releasable. On
retry it can therefore call xsk_buff_free() again through stale pointers
after the frames have returned to the XSK pool and been reallocated.
Set all skip_release_bitmap bits in the common error path of
mlx5e_xsk_alloc_rx_mpwqe(). This matches mlx5e_alloc_rx_mpwqe(). A
successful allocation already clears the bitmap after replacing every
buffer, so retries become idempotent without changing the success path.
Fault injection forced three consecutive failures for one selected MPWQE.
Both an early allocation failure and a partial 8-of-16-buffer unwind
released the original 16 XSK buffers only once. Each error left a full
bitmap, the following NAPI retry skipped the release, and a later
successful allocation cleared it. A 20-second AF_XDP zero-copy pressure
run exercised 1,575,262 buffer allocation failures without invalid
descriptors, WQE errors, or kernel warnings.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
4c2a1323680709078736a2886c754004e9fe42e6 before f3a52e2ec2788a7f6b64137985c087188a54ad4f; 4c2a1323680709078736a2886c754004e9fe42e6 before d215d09606b0fcd18ad1eb532995782a21cea49d; 4c2a1323680709078736a2886c754004e9fe42e6 before 867119b4b588037724b85839d534465f0334d9bd; 4c2a1323680709078736a2886c754004e9fe42e6 before 3d73a1164a8c6b4461907a65cb6c022ea4fd39af; 4c2a1323680709078736a2886c754004e9fe42e6 before 63811edf512584c946e5e96b100e9e280703bbb5; 6.4 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-99078
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-99078
git.kernel.org
https://git.kernel.org/stable/c/3d73a1164a8c6b4461907a65cb6c022ea4fd39af
git.kernel.org
https://git.kernel.org/stable/c/63811edf512584c946e5e96b100e9e280703bbb5
git.kernel.org
https://git.kernel.org/stable/c/867119b4b588037724b85839d534465f0334d9bd
git.kernel.org
https://git.kernel.org/stable/c/d215d09606b0fcd18ad1eb532995782a21cea49d
git.kernel.org
https://git.kernel.org/stable/c/f3a52e2ec2788a7f6b64137985c087188a54ad4f
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