CVE-2021-47527

Advisory lineage Upstream: 0 Downstream: 5
Analyzed
Published: 24 May 2024, 15:09
Last modified:11 May 2026, 13:56

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
<0.01% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

24 May 2024, 15:09
Published
Vulnerability first disclosed
11 May 2026, 13:56
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: serial: core: fix transmit-buffer reset and memleak Commit 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") converted serial core to use tty_port_close() but failed to notice that the transmit buffer still needs to be freed on final close. Not freeing the transmit buffer means that the buffer is no longer cleared on next open so that any ioctl() waiting for the buffer to drain might wait indefinitely (e.g. on termios changes) or that stale data can end up being transmitted in case tx is restarted. Furthermore, the buffer of any port that has been opened would leak on driver unbind. Note that the port lock is held when clearing the buffer pointer due to the ldisc race worked around by commit a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()"). Also note that the tty-port shutdown() callback is not called for console ports so it is not strictly necessary to free the buffer page after releasing the lock (cf. d72402145ace ("tty/serial: do not free trasnmit buffer page under port lock")).

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.01%• Percentile: 1%

Techniques & Countermeasures

  • CWE-401•Missing Release of Memory after Effective Lifetime

    The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Systems

  • linux•linux

    ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < 011f6c92b5bf6e1fbfdedc8b5232f64c1c493206 | ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < e74d9663fd57640fc3394abb5c76fa95b9cc2f2e | ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < 1179b168fa3f3a6aae3bd140000455a0e58457db | ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < c5da8aa441053958594f94254592bb41264bdfbf | ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < e1722acf4f0d4d67b60f57e08ce16f8b66cd4b8f | ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < 64e491c1634b73d3bddc081d08620bdc92ab2c12 | ≥ 761ed4a94582ab291aa24dcbea4e01e8936488c8, < 00de977f9e0aa9760d9a79d1e41ff780f74e3424 | 4.9

  • linux•linux_kernel

    ≥ 4.9, < 4.9.292 | ≥ 4.10, < 4.14.257 | ≥ 4.15, < 4.19.220 | ≥ 4.20, < 5.4.164 | ≥ 5.5, < 5.10.84 | ≥ 5.11, < 5.15.7 | 5.16:rc1 | 5.16:rc2 | 5.16:rc3

References (7)