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CVE-2026-98591

Unknown

Last modified

CVE-2026-98591 is a vulnerability of currently unknown severity. In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bounds check for skb-backed dynptrs The skb_pointer_if_linear() function checks whether a memory region of length len starting at offset off into the skb is in the linear area, and returns a pointer to the region if so. The check currently subtracts between skb_headlen and offset of the check, and since skb_headlen is unsigned the subtraction can underflow.

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bounds check for skb-backed dynptrs The skb_pointer_if_linear() function checks whether a memory region of length len starting at offset off into the skb is in the linear area, and returns a pointer to the region if so. The check currently subtracts between skb_headlen and offset of the check, and since skb_headlen is unsigned the subtraction can underflow. This causes the bounds check to spuriously pass and generate an arbitrary pointer of the form *(skb->data + off). The only user of this helper is currently skb-backed BPF dynptr code. Returning the wrong pointer leads to the dynptr erroneously being backed with invalid memory. Ensure the subtraction cannot underflow, and fail the check if it would. Use u64 arithmetic to also prevent overflow when calculating (skb_headlen(skb) - off) since off is unsigned.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 6f5a630d7c57cd79b1f526a95e757311e32d41e5, < 1b923538598be768e9f2f258a77a083d00e0c78b; >= 6f5a630d7c57cd79b1f526a95e757311e32d41e5, < 37877a24758068742fef687a7cf5362360dde1d1; >= 6f5a630d7c57cd79b1f526a95e757311e32d41e5, < 1196903a27cac5c929c7517e987a8d159f20c5e5; >= 6f5a630d7c57cd79b1f526a95e757311e32d41e5, < 39ffceaddb10753eac12785dba6ac0673860b4ac; >= 6f5a630d7c57cd79b1f526a95e757311e32d41e5, < ed6eec97b534979dcf28b40c389cee57bd6561d4
LinuxLinux6.6

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-98591?
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bounds check for skb-backed dynptrs The skb_pointer_if_linear() function checks whether a memory region of length len starting at offset off into the skb is in the linear area, and returns a pointer to the region if so. The check currently subtracts between skb_headlen and offset of the check, and since skb_headlen is unsigned the subtraction can underflow. This causes the bounds check to spuriously pass and generate an arbitrary pointer of the form *(skb->data + off). The only user of this helper is currently skb-backed BPF dynptr code. Returning the wrong pointer leads to the dynptr erroneously being backed with invalid memory. Ensure the subtraction cannot underflow, and fail the check if it would. Use u64 arithmetic to also prevent overflow when calculating (skb_headlen(skb) - off) since off is unsigned.
How severe is CVE-2026-98591?
Severity scoring for CVE-2026-98591 is pending analysis.
How do I fix CVE-2026-98591?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST