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CVE-2026-98591— bpf: Fix bounds check for skb-backed dynptrs

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： bpf：修复基于 skb 的 dynptr 的边界检查 skb_pointer_if_linear() 函数用于检查从 skb 的偏移量 off 开始、长度为 len 的内存区域是否位于线性区；如果位于线性区，则返回指向该区域的指针。当前的检查逻辑会计算 skb_headlen 与偏移量 off 之间的差值。由于 skb_headlen 是无符号整数，该减法可能导致下溢（underflow），从而使边界检查错误地通过，并生成形式为 *(skb->data + off)

AI Predicted 7.8 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 6f5a630d7c57cd79b1f526a95e757311e32d41e5< 1b923538598be768e9f2f258a77a083d00e0c78b affected
6f5a630d7c57cd79b1f526a95e757311e32d41e5< 37877a24758068742fef687a7cf5362360dde1d1 affected
6f5a630d7c57cd79b1f526a95e757311e32d41e5< 1196903a27cac5c929c7517e987a8d159f20c5e5 affected
6f5a630d7c57cd79b1f526a95e757311e32d41e5< 39ffceaddb10753eac12785dba6ac0673860b4ac affected
6f5a630d7c57cd79b1f526a95e757311e32d41e5< ed6eec97b534979dcf28b40c389cee57bd6561d4 affected
6.6 affected
< 6.6 unaffected
6.6.158≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-98591

Vulnerability Information
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Vulnerability Title
bpf: Fix bounds check for skb-backed dynptrs
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 6f5a630d7c57cd79b1f526a95e757311e32d41e5 ~ 1b923538598be768e9f2f258a77a083d00e0c78b -
Linux Linux 6.6 -

II. Public POCs for CVE-2026-98591

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III. Intelligence Information for CVE-2026-98591

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Other References for CVE-2026-98591 (5)

Same Patch Batch · Linux · 2026-10-18 · 436 CVEs total

CVE-2026-98582 nfc: st21nfca: validate received frame size
CVE-2026-98568 vxlan: use one headroom snapshot for neighbour replies
CVE-2026-98570 net: ipv6: keep room for the mac header in dst_dev_overhead()
CVE-2026-98571 net: stmmac: clear stale buf->page after recycling on skb build failure
CVE-2026-98572 bpf: Fix immediate JMP JEQ/JNE on MIPS32
CVE-2026-98573 net: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6()
CVE-2026-98574 net: bcmgenet: stop Tx NAPI before disabling the queues
CVE-2026-98575 nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid()
CVE-2026-98576 nfc: llcp: fix slab-out-of-bounds reads when logging service names
CVE-2026-98577 nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap()
CVE-2026-98578 nfc: st21nfca: validate ISO15693 inventory length
CVE-2026-98579 nfc: llcp: fix sdreq TLV list leak on parse/alloc/send failure
CVE-2026-98580 nfc: llcp: Fix race condition in accept_queue lifecycle
CVE-2026-98581 nfc: llcp: Fix list corruption / refcount desync in nfc_llcp_recv_dm()
CVE-2026-98594 tg3: clean up PHYLIB resources on probe failure
CVE-2026-98590 bpf: Fix bpf_sock context code generation
CVE-2026-98592 net: spacemit: clear TX descriptor on fragment mapping failure
CVE-2026-98593 s390/debug: Fix NULL pointer dereference in debug_info_copy()
CVE-2026-98589 bpf: Reject pkt arguments in mutating subprogs
CVE-2026-98595 udp: remove a disconnected socket from the 4-tuple hash table

Showing top 20 of 436 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98591

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