CVE-2025-39724: serial: 8250: fix panic due to PSLVERR
Vulnerability summary
CVE-2025-39724 is a medium (CVSS 5.5) vulnerability in debian debian_linux. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 6.8% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 47 · Related 41Timeline
- 05-09-2025PublishedVulnerability first disclosed.
- 15-10-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: serial: 8250: fix panic due to PSLVERR When the PSLVERR_RESP_EN parameter is set to 1, the device generates an error response if an attempt is made to read an empty RBR (Receive Buffer Register) while the FIFO is enabled. In serial8250_do_startup(), calling serial_port_out(port, UART_LCR, UART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes dw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter function enables the FIFO via serial_out(p, UART_FCR, p->fcr). Execution proceeds to the serial_port_in(port, UART_RX). This satisfies the PSLVERR trigger condition. When another CPU (e.g., using printk()) is accessing the UART (UART is busy), the current CPU fails the check (value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter dw8250_force_idle(). Put serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock to fix this issue. Panic backtrace: [ 0.442336] Oops - unknown exception [#1] [ 0.442343] epc : dw8250_serial_in32+0x1e/0x4a [ 0.442351] ra : serial8250_do_startup+0x2c8/0x88e ... [ 0.442416] console_on_rootfs+0x26/0x70
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.17%
Chance of exploitation in the next 30 days
Percentile
7%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.17% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu148 products
- linuxAll versions (No fix recorded) | < 5.15.0-163.173 | < 6.8.0-100.100
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1097.104 | < 6.8.0-1046.49
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.1.153-1 | < 6.12.48-1 | < 6.16.5-1
- debian_linuxEOL11.0
Linux2 products
- linux≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < 0b882f00655afefbc7729c6b5aec86f7a5473a3d | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < b8ca8e3f75ede308b4d49a6ca5081460be01bdb5 | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < 68c4613e89f000e8198f9ace643082c697921c9f | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < c826943abf473a3f7260fbadfad65e44db475460 | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < cb7b3633ed749db8e56f475f43c960652cbd6882 | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < 8e2739478c164147d0774802008528d9e03fb802 | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < 38c0ea484dedb58cb3a4391229933e16be0d1031 | ≥ c49436b657d0a56a6ad90d14a7c3041add7cf64d, < 7f8fdd4dbffc05982b96caf586f77a014b2a9353 | 6d5e79331417886196cb3a733bdb6645ba85bc42 | 2401577586898b3590db80f8b97a26f81f0f6d4e | ≥ 3.10.48, < 3.11 | ≥ 3.12.24, < 3.13 | 3.13
- linux_kernel≥ 3.10.48, < 3.11 | ≥ 3.12.24, < 5.4.297 | ≥ 5.5, < 5.10.241 | ≥ 5.11, < 5.15.190 | ≥ 5.16, < 6.1.149 | ≥ 6.2, < 6.6.103 | ≥ 6.7, < 6.12.44 | ≥ 6.13, < 6.16.4
3 vendors · 152 products
