CVE-2021-47307: cifs: prevent NULL deref in cifs_compose_mount_options()
Vulnerability summary
CVE-2021-47307 is a high (CVSS 7.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.69% chance of exploitation in the next 30 days, higher than 52.8% of scored vulnerabilities.
Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 6 · Related 6Timeline
- 21-05-2024PublishedVulnerability first disclosed.
- 05-08-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: cifs: prevent NULL deref in cifs_compose_mount_options() The optional @ref parameter might contain an NULL node_name, so prevent dereferencing it in cifs_compose_mount_options(). Addresses-Coverity: 1476408 ("Explicit null dereferenced")
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/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:HDiffers
- NVDNIST5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
EPSS trend
Probability
0.69%
Chance of exploitation in the next 30 days
Percentile
53%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.69% 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 causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu88 products
- linuxAll versions (No fix recorded) | < 5.4.0-88.99
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.4.0-1057.60
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 2c55608f28444c3f33b10312881384c470ceed56, < f7d1fa65e74263d11f90ddd33b4d4cd905a93759 | ≥ 2c55608f28444c3f33b10312881384c470ceed56, < e58c162789becede894d3e94c0ce6695a2ef5796 | ≥ 2c55608f28444c3f33b10312881384c470ceed56, < ae3d181f4e912f51af7776ea165f199b16fc165d | ≥ 2c55608f28444c3f33b10312881384c470ceed56, < 03313d1c3a2f086bb60920607ab79ac8f8578306 | 2.6.28
- linux_kernel< 5.4.135 | ≥ 5.5, < 5.10.53 | ≥ 5.11, < 5.13.5
Debian1 product
- linux< 5.14.6-1
3 vendors · 91 products
