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CVE-2025-38591— bpf: Reject narrower access to pointer ctx fields

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.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于bpf模块在访问指针ctx字段时拒绝较窄的访问。

AI Predicted 5.0 Difficulty: Moderate EPSS 0.21% · P11

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux f96da09473b52c09125cc9bf7d7d4576ae8229e0< 7847c4140e06f6e87229faae22cc38525334c156 affected
f96da09473b52c09125cc9bf7d7d4576ae8229e0< feae34c992eb7191862fb1594c704fbbf650fef8 affected
f96da09473b52c09125cc9bf7d7d4576ae8229e0< 33660d44e789edb4f303210c813fc56d56377a90 affected
f96da09473b52c09125cc9bf7d7d4576ae8229e0< e2e9599f3503df7cf3569d2b6c50d5488fb59435 affected
f96da09473b52c09125cc9bf7d7d4576ae8229e0< 058a0da4f6d916a79b693384111bb80a90d73763 affected
f96da09473b52c09125cc9bf7d7d4576ae8229e0< 202900ceeef67458c964c2af6e1427c8e533ea7c affected
f96da09473b52c09125cc9bf7d7d4576ae8229e0< e09299225d5ba3916c91ef70565f7d2187e4cca0 affected
4.13 affected
… +8 more rows
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I. Basic Information for CVE-2025-38591

Vulnerability Information
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Vulnerability Title
bpf: Reject narrower access to pointer ctx fields
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject narrower access to pointer ctx fields The following BPF program, simplified from a syzkaller repro, causes a kernel warning: r0 = *(u8 *)(r1 + 169); exit; With pointer field sk being at offset 168 in __sk_buff. This access is detected as a narrower read in bpf_skb_is_valid_access because it doesn't match offsetof(struct __sk_buff, sk). It is therefore allowed and later proceeds to bpf_convert_ctx_access. Note that for the "is_narrower_load" case in the convert_ctx_accesses(), the insn->off is aligned, so the cnt may not be 0 because it matches the offsetof(struct __sk_buff, sk) in the bpf_convert_ctx_access. However, the target_size stays 0 and the verifier errors with a kernel warning: verifier bug: error during ctx access conversion(1) This patch fixes that to return a proper "invalid bpf_context access off=X size=Y" error on the load instruction. The same issue affects multiple other fields in context structures that allow narrow access. Some other non-affected fields (for sk_msg, sk_lookup, and sockopt) were also changed to use bpf_ctx_range_ptr for consistency. Note this syzkaller crash was reported in the "Closes" link below, which used to be about a different bug, fixed in commit fce7bd8e385a ("bpf/verifier: Handle BPF_LOAD_ACQ instructions in insn_def_regno()"). Because syzbot somehow confused the two bugs, the new crash and repro didn't get reported to the mailing list.
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
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于bpf模块在访问指针ctx字段时拒绝较窄的访问。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux f96da09473b52c09125cc9bf7d7d4576ae8229e0 ~ 7847c4140e06f6e87229faae22cc38525334c156 -
Linux Linux 4.13 -

II. Public POCs for CVE-2025-38591

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III. Intelligence Information for CVE-2025-38591

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Patches & Fixes for CVE-2025-38591 (1)

Same Patch Batch · Linux · 2025-08-19 · 59 CVEs total

CVE-2025-38561 9.8 CRITICAL ksmbd: fix Preauh_HashValue race condition
CVE-2025-38566 9.8 CRITICAL sunrpc: fix handling of server side tls alerts
CVE-2025-38560 9.3 CRITICAL x86/sev: Evict cache lines during SNP memory validation
CVE-2025-38601 8.8 HIGH wifi: ath11k: clear initialized flag for deinit-ed srng lists
CVE-2025-38600 8.8 HIGH wifi: mt76: mt7925: fix off by one in mt7925_mcu_hw_scan()
CVE-2025-38599 8.8 HIGH wifi: mt76: mt7996: Fix possible OOB access in mt7996_tx()
CVE-2025-38592 8.8 HIGH Bluetooth: hci_devcd_dump: fix out-of-bounds via dev_coredumpv
CVE-2025-38608 8.6 HIGH bpf, ktls: Fix data corruption when using bpf_msg_pop_data() in ktls
CVE-2025-38574 8.6 HIGH pptp: ensure minimal skb length in pptp_xmit()
CVE-2025-38571 8.2 HIGH sunrpc: fix client side handling of tls alerts
CVE-2025-38615 7.8 HIGH fs/ntfs3: cancle set bad inode after removing name fails
CVE-2025-38579 7.8 HIGH f2fs: fix KMSAN uninit-value in extent_info usage
CVE-2025-38604 7.8 HIGH wifi: rtl818x: Kill URBs before clearing tx status queue
CVE-2025-38607 7.8 HIGH bpf: handle jset (if a & b ...) as a jump in CFG computation
CVE-2025-38614 7.8 HIGH eventpoll: Fix semi-unbounded recursion
CVE-2025-38593 7.8 HIGH Bluetooth: hci_sync: fix double free in 'hci_discovery_filter_clear()'
CVE-2025-38586 7.8 HIGH bpf, arm64: Fix fp initialization for exception boundary
CVE-2025-38582 7.8 HIGH RDMA/hns: Fix double destruction of rsv_qp
CVE-2025-38580 7.8 HIGH ext4: fix inode use after free in ext4_end_io_rsv_work()
CVE-2025-38555 7.8 HIGH usb: gadget : fix use-after-free in composite_dev_cleanup()

Showing top 20 of 59 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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