CVE-2018-20856: linux linux_kernel Use After Free

Modified

AliasesRHSA-2020:0698UBUNTU-CVE-2018-20856DEBIAN-CVE-2018-20856

Published 26-07-2019Last modified 05-08-2024

Vulnerability summary

CVE-2018-20856 is a high (CVSS 7.8) Use After Free vulnerability in linux linux_kernel. EPSS estimates a 0.71% chance of exploitation in the next 30 days, higher than 53.4% of scored vulnerabilities.

Priority

Routine

Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?

CVSS score

7.8/10

010

High · v3.0 (NVD)

EPSS score

0.71%

0%100%

Low · 0.00 pp in 30 days

KEVNot listedNot listed by any tracked catalog.

RansomwareNot flaggedNo ransomware use recorded.

Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 21 · Related 11

Timeline

26-07-2019
PublishedVulnerability first disclosed.
05-08-2024
Last modifiedVulnerability information updated.

Description

An issue was discovered in the Linux kernel before 4.18.7. In block/blk-core.c, there is an __blk_drain_queue() use-after-free because a certain error case is mishandled.

CVSS metrics

5 scores · 4 sources · 2 versions

v3.07.8v2.04.6

EPSS trend

Probability

0.71%

Chance of exploitation in the next 30 days

Percentile

53%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.71% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs

CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu23 products

linux< 4.4.0-161.189 | < 4.15.0-58.64
linux-aws< 4.4.0-1054.58 | < 4.4.0-1092.103 | < 4.15.0-1047.49
linux-aws-fips< 4.15.0-2018.18 | All versions (No fix recorded)
linux-aws-hwe< 4.15.0-1047.49~16.04.1
linux-azure< 4.15.0-1059.64~14.04.1 | < 4.15.0-1055.60 | < 4.18.0-1011.11~18.04.1