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CVE-2026-74751— riscv: lib: Fix ZBB strnlen reading past count boundary

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，已解决以下漏洞： riscv: lib: 修复 ZBB 优化的 strnlen 越界读取问题 ZBB 优化的 循环在检查对齐边界之前，会提前加载下一个字： 其中 。当 对齐且 是 的倍数时， 等于 ，此时循环会在恰好位于 的位置加载一个完整的字。如果 恰好落在页边界上，且下一页未映射，则会触发缺页异常（fault）。 修复方案： 1. 通过基于最后一个有效字节（即 ）而非 来计算对齐边界。这样循环会在包含最后一个有效字节的字处停止，而不会继续加载其后的字。 的情况已由 提前退出处理。 2.

CVSS 9.4 · Critical

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 5ba15d419fab848a3813eb56bbcad00e291fbc49< e697e30f3dd2da3a1df7dc0980546d5b53aea4b6 affected
5ba15d419fab848a3813eb56bbcad00e291fbc49< 5d588c684833e678a0008eb69c33190f01a65f4b affected
7.1 affected
< 7.1 unaffected
7.1.10≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-74751

Vulnerability Information
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Vulnerability Title
riscv: lib: Fix ZBB strnlen reading past count boundary
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: riscv: lib: Fix ZBB strnlen reading past count boundary The ZBB-optimized strnlen loop loads one word ahead before checking the aligned boundary: REG_L t1, SZREG(t0) // load next word addi t0, t0, SZREG // advance orc.b t1, t1 bgeu t0, t4, 4f // boundary check AFTER load where t4 = (s + count) & -SZREG. When s is aligned and count is a multiple of SZREG, t4 equals s + count and the loop loads a full word starting at exactly s + count. If s + count falls on a page boundary with the next page unmapped, this faults. Fix by computing the aligned boundary from the last valid byte (s + count - 1) instead of s + count. This makes the loop stop at the word containing the last valid byte rather than potentially loading the word after it. The count == 0 case is already handled by the beqz early exit. Also add a pre-loop guard (bgeu t0, t4) for the case where all valid bytes fit within the first word. With the adjusted boundary, t4 can equal t0, and entering the loop with stale register state from the first-word processing would produce incorrect results. The final minu clamp ensures the result is still correct when the last loaded word extends past s + count - 1 within the same aligned word.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
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 5ba15d419fab848a3813eb56bbcad00e291fbc49 ~ e697e30f3dd2da3a1df7dc0980546d5b53aea4b6 -
Linux Linux 7.1 -

II. Public POCs for CVE-2026-74751

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III. Intelligence Information for CVE-2026-74751

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Patches & Fixes for CVE-2026-74751 (2)

Same Patch Batch · Linux · 2026-08-26 · 92 CVEs total

CVE-2026-74752 9.8 CRITICAL sctp: validate cookie AUTH state before use
CVE-2026-80589 9.8 CRITICAL block: stop the timeout timer when releasing a never added disk
CVE-2026-74737 9.8 CRITICAL net: ethernet: ti: am65-cpsw-nuss: Fix port_id extraction from SRC TAG
CVE-2026-80557 9.8 CRITICAL libceph: fix OOB read in decode_watchers() via missing bounds check
CVE-2026-80587 9.8 CRITICAL mptcp: avoid combining some incoming suboptions
CVE-2026-80528 9.8 CRITICAL ceph: avoid fs reclaim while using current->journal_info
CVE-2026-80561 9.8 CRITICAL libceph: fix multiple unsafe decodes in decode_locker()
CVE-2026-74743 9.8 CRITICAL macvlan: inherit needed_headroom and needed_tailroom from lowerdev
CVE-2026-74744 9.8 CRITICAL ipvlan: inherit needed_headroom and needed_tailroom from phy_dev
CVE-2026-80586 9.8 CRITICAL mptcp: options: reset DSS fields in case of unexpected size
CVE-2026-74746 9.8 CRITICAL netfilter: flowtable: publish GC-visible tuple last
CVE-2026-80558 9.8 CRITICAL libceph: Avoid using invalid osd indices from primary_temp
CVE-2026-80519 9.8 CRITICAL ovpn: finish crypto callback cleanup before peer release
CVE-2026-80585 9.4 CRITICAL mptcp: fastopen: only mark MPTFO subflows with SYN data
CVE-2026-80554 9.3 CRITICAL s390/vfio_ccw: Limit the number of channel program segments
CVE-2026-80551 9.3 CRITICAL s390/vfio_ccw: Ensure first IDAW remains constant
CVE-2026-80576 8.8 HIGH drm/amdgpu: reject oversized IBs with per-ring packet limits
CVE-2026-80547 8.8 HIGH s390/vfio_ccw: Implement a crw lock
CVE-2026-80552 8.8 HIGH s390/vfio_ccw: Ensure index for read/write regions are within range
CVE-2026-80548 8.8 HIGH s390/vfio_ccw: Selectively expand io_mutex

Showing top 20 of 92 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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