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CVE-2026-74478— um: vector: fix use-after-free in vector_mmsg_rx()

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基金会开源的一个操作系统内核。 Linux kernel 4.17版本存在安全漏洞，该漏洞源于vector_mmsg_rx()函数在处理verify_header()失败的报文时未清除已释放的skb槽位，导致释放后重用，可能造成引用计数下溢。

CVSS 9.8 · Critical EPSS 0.57% · P45

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< 967c779c9853d2a1cc9cd8e61d300250c348f3d9 affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< a7bc015bb798c525e7a82dd14225c6aeb994274b affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< 7dc9781e320d664c9bdd50003c9acfddf363d1e1 affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< 4b9601595e8b6b5d18878cac0aeabc687d241111 affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< 67d58ab4f2ccf7145f3da07e025735a09c79de1b affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< 180ff4c81faf01ec4e06082c9daa7c40518ead89 affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< 804b681002ead233abf49a3efd681f5468a835f9 affected
49da7e64f33e80edffb1a9eeb230fa4c3f42dffb< af421e9aed3920c7ac88c24daa48606c7112feca affected
… +10 more rows
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I. Basic Information for CVE-2026-74478

Vulnerability Information
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Vulnerability Title
um: vector: fix use-after-free in vector_mmsg_rx()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: um: vector: fix use-after-free in vector_mmsg_rx() When vector_mmsg_rx() discards a packet whose overlay header fails verify_header(), it frees the skb and continues the loop: if (header_check < 0) { dev_kfree_skb_irq(skb); vp->estats.rx_encaps_errors++; continue; } The normal and short-packet paths fall through to the bottom of the loop body, which clears the consumed slot and advances the cursors: (*skbuff_vector) = NULL; mmsg_vector++; skbuff_vector++; The verify_header() < 0 path skips that via continue, so the freed skb is left in skbuff_vector[] and the cursors do not advance. The next iteration reads the same slot, gets the freed skb, and frees it again, producing a refcount underflow / use-after-free in the RX path. Discard the slot the same way the other paths do before continuing. Only transports whose verify_header() can return negative are affected: GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not), so any peer on such a transport can trigger it without authentication.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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基金会开源的一个操作系统内核。 Linux kernel 4.17版本存在安全漏洞，该漏洞源于vector_mmsg_rx()函数在处理verify_header()失败的报文时未清除已释放的skb槽位，导致释放后重用，可能造成引用计数下溢。
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 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb ~ 967c779c9853d2a1cc9cd8e61d300250c348f3d9 -
Linux Linux 4.17 -

II. Public POCs for CVE-2026-74478

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III. Intelligence Information for CVE-2026-74478

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Patches & Fixes for CVE-2026-74478 (8)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-74427 9.8 CRITICAL afs: Fix netns teardown to cancel the preallocation charger
CVE-2026-72211 9.8 CRITICAL ntfs: grow index root value before reparent header update
CVE-2026-72209 9.8 CRITICAL ntfs: validate attribute values on lookup
CVE-2026-72208 9.8 CRITICAL ntfs: add bounds check before accessing EA entries
CVE-2026-72299 9.8 CRITICAL tipc: restrict socket queue dumps in enqueue tracepoints
CVE-2026-74434 9.8 CRITICAL rxrpc: Don't move a peeked OOB message onto the pending queue
CVE-2026-74433 9.8 CRITICAL rxrpc: Fix UAF in rxgk_issue_challenge()
CVE-2026-72473 9.8 CRITICAL xprtrdma: Decouple req recycling from RPC completion
CVE-2026-72472 9.8 CRITICAL nfs: use nfsi->rwsem to protect traversal of the file lock list
CVE-2026-74545 9.8 CRITICAL rtase: fix double free of multi-frag skb on DMA map failure
CVE-2026-72046 9.8 CRITICAL gve: fix header buffer corruption with header-split and HW-GRO
CVE-2026-72466 9.8 CRITICAL xprtrdma: Fix bcall rep leak and unbounded peek

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74478

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