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CVE-2026-98591

Linux: bpf: Fix bounds check for skb-backed dynptrs

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.20%Chance of exploitation activity in the next 30 days, higher than 9% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1b923538598be768e9f2f258a77a083d00e0c78bAlso 37877a24758068742fef687a7cf5362360dde1d1, 1196903a27cac5c929c7517e987a8d159f20c5e5 and 1 moreCVE List
Published18 Oct 2026Updated 19 Oct 2026CVE List

What fixes it

  • 1b923538598be768e9f2f258a77a083d00e0c78bLinuxCVE List
  • 37877a24758068742fef687a7cf5362360dde1d1LinuxCVE List
  • 1196903a27cac5c929c7517e987a8d159f20c5e5LinuxCVE List
  • 39ffceaddb10753eac12785dba6ac0673860b4acLinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 12

  • Linuxaffected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 before 1b923538598be768e9f2f258a77a083d00e0c78bCVE List
  • Linuxaffected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 before 37877a24758068742fef687a7cf5362360dde1d1CVE List
  • Linuxaffected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 before 1196903a27cac5c929c7517e987a8d159f20c5e5CVE List
  • Linuxaffected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 before 39ffceaddb10753eac12785dba6ac0673860b4acCVE List
  • Linuxaffected: 6f5a630d7c57cd79b1f526a95e757311e32d41e5 before ed6eec97b534979dcf28b40c389cee57bd6561d4CVE List
  • Linuxaffected: 6.6CVE List
  • Linuxunaffected: all versions before 6.6CVE List
  • Linuxunaffected: 6.6.158 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.55 through 6.18.*CVE List
  • Linuxunaffected: 7.2.9 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5