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CVE-2026-74653— serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx

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.

以下是该漏洞描述信息的中文翻译： 在 Linux 内核中，已修复以下漏洞： serial: 8250_of: 清除 LPC32xx 上卡滞的空 FIFO RX 超时状态 NXP LPC32xx UART（PORT_LPC3220）会在 RX FIFO 为空时锁存（latch）一个 RX 字符超时中断：IIR 报告 UART_IIR_RX_TIMEOUT (0x0c)，但 LSR.DR 位为清除状态。只有读取 RHR 才能清除字符超时状态，但 仅在 LSR.DR 置位时才读取 RHR，因此该条件永远无法被清除。由于该

AI Predicted 5.9 Difficulty: Moderate EPSS 0.21% · P11

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 3ce24bc4d115336218e59b7e286fd3a79f4fc4c6 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 7795e8abedc86438cae0454602cbf9038b94bf38 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 1423415471274abda87024967d7fe2206ceee0ea affected
< 6.18.45 affected
< 7.1.9 affected
6.18.45≤ 6.18.* unaffected
7.1.9≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-74653

Vulnerability Information
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Vulnerability Title
serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx The NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout interrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT (0x0c) but LSR.DR is clear. A character timeout is only cleared by reading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is set, so nothing ever clears the condition. The interrupt is level-triggered and re-fires immediately, so on a single-core ARM926 the resulting interrupt storm livelocks the CPU. It is reproducible when userspace repeatedly opens the front-panel port (ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and the handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping the soft-lockup detector in serial8250_handle_irq_locked(). LPC32xx has no dedicated 8250 glue driver, it's driven by the generic 8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up in of_platform_serial_setup() the same way fsl8250_handle_irq is installed. The handler follows dw8250_handle_irq(): on an RX timeout with an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR read to clear the condition, then calls serial8250_handle_irq_locked(). No real received data is ever discarded, and it is a no-op on healthy UARTs which never report a timeout with DR clear. This is the same class of bug already worked around in other 8250 drivers; see commit 424d79183af0 ("serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt") which reports the identical iir=0xcc/lsr=0x60. See also UART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271.
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 e6e912c4964ce5976e508881207dfa96d5f856d7 ~ 3ce24bc4d115336218e59b7e286fd3a79f4fc4c6 -
Linux Linux 2.6.36 -

II. Public POCs for CVE-2026-74653

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III. Intelligence Information for CVE-2026-74653

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Patches & Fixes for CVE-2026-74653 (3)

Same Patch Batch · Linux · 2026-08-22 · 150 CVEs total

CVE-2026-74705 10.0 CRITICAL udp: fix potential use-after-free in tunnel segmentation
CVE-2026-74612 10.0 CRITICAL veth: fix skb length accounting after XDP frag adjustment
CVE-2026-74588 9.8 CRITICAL sctp: keep chunk->transport in step with the list it is queued on
CVE-2026-74628 9.8 CRITICAL net/x25: fix use-after-free of the socket by its timers
CVE-2026-74669 9.8 CRITICAL ipvs: clear IPv4 options after rebasing tunnel ICMP errors
CVE-2026-74597 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
CVE-2026-74608 9.8 CRITICAL smb: client: Fix use-after-free in cifs_try_adding_channels()
CVE-2026-74662 9.8 CRITICAL inet: frags: publish queues before arming timer
CVE-2026-74611 9.8 CRITICAL tls: rx: restore msg_iter before TLS 1.3 optimistic retry
CVE-2026-74587 9.8 CRITICAL sctp: fix use-after-free of cached ASCONF chunk
CVE-2026-74688 9.8 CRITICAL sctp: clear control chunk transport if it is being removed
CVE-2026-74723 9.8 CRITICAL btrfs: lzo: reject inline extents without valid headers
CVE-2026-74617 9.8 CRITICAL dibs: initialise dibs->lock in dibs_dev_alloc()
CVE-2026-74616 9.8 CRITICAL xdp: reject clones that overrun skb_shared_info tailroom
CVE-2026-74591 9.8 CRITICAL mm/filemap: __filemap_add_folio() restore index before retrying
CVE-2026-74586 9.8 CRITICAL sctp: clear new_transport when removing a peer
CVE-2026-74730 9.8 CRITICAL NFS: Pin the 'struct nfs_server' during a FREE_STATEID call
CVE-2026-74727 9.8 CRITICAL ovpn: skip rehash for peers already removed from by_id
CVE-2026-74712 9.3 CRITICAL vdpa/mlx5: Fix buffer length in create_direct_keys()
CVE-2026-74665 9.1 CRITICAL net: fix skb length accounting after generic XDP frag adjustment

Showing top 20 of 150 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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