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Public proof of conceptFix available

CVE-2021-27365

A public proof of concept exists; no exploitation attested.

  • Published2021-03-07
  • Fixed in5.11.4 · 5.10.21 · 5.4.103 · 4.19.179 · 4.14.224 · 4.9.260
  • WeaknessCWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An issue was discovered in the Linux kernel through 5.11.3. Certain iSCSI data structures do not have appropriate length constraints or checks, and can exceed the PAGE_SIZE value. An unprivileged user can send a Netlink message that is associated with iSCSI, and has a length up to the maximum length of a Netlink message.

Timeline

dates in UTC
  1. 2021-03-0705:15CVE publishedNVD

Versions per branch

NVD
Linux linux kernel
BranchAffectedFixed in
5.11≥ 5.11, < 5.11.45.11.4
5.x≥ 5.5, < 5.10.215.10.21
5.4≥ 4.20, < 5.4.1035.4.103
4.x≥ 4.15, < 4.19.1794.19.179
4.x≥ 4.10, < 4.14.2244.14.224
4.x≥ 4.5, < 4.9.2604.9.260
4.4< 4.4.2604.4.260
Debian debian linux
BranchAffectedFixed in
9.0= 9.0no fix published
Netapp cloud backup
BranchAffectedFixed in
—all versionsno fix published

2 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • kernelTuxCare:OracleLinux:6all versions · fixed in 2.6.32-754.35.2.el6and 6 other packages
  • kernelTuxCare:CentOS:6all versions · fixed in 2.6.32-754.35.3.el6and 7 other packages
  • kernelRed Hat:rhel_tus:7.4::serverall versions · fixed in 0:3.10.0-693.84.1.el7and 16 other packages
  • kernelRed Hat:rhel_eus:8.2::baseosall versions · fixed in 0:4.18.0-193.51.1.el8_2and 32 other packages
  • kernelRed Hat:rhel_eus:8.1::baseosall versions · fixed in 0:4.18.0-147.44.1.el8_1and 32 other packages
  • kernelRed Hat:rhel_eus:7.7::serverall versions · fixed in 0:3.10.0-1062.49.1.el7and 25 other packages
  • kernelRed Hat:rhel_eus:7.7::computenodeall versions · fixed in 0:3.10.0-1062.49.1.el7and 18 other packages
  • kernelRed Hat:rhel_eus:7.6::serverall versions · fixed in 0:3.10.0-957.72.1.el7and 24 other packages

251 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-27365 Red Hat Product Security1,339 products fixed

    kernel: heap buffer overflow in the iSCSI subsystem

  • RHSA-2021:1531 Red Hat Product Security120 products fixed

    Red Hat Security Advisory: kernel security and bug fix update

  • RHSA-2021:1532 Red Hat Product Security55 products fixed

    Red Hat Security Advisory: kpatch-patch security update

  • RHSA-2021:1376 Red Hat Product Security111 products fixed

    Red Hat Security Advisory: kernel security and bug fix update

  • RHSA-2021:1377 Red Hat Product Security45 products fixed

    Red Hat Security Advisory: kpatch-patch security update

  • RHSA-2021:1379 Red Hat Product Security23 products fixed

    Red Hat Security Advisory: kernel-alt security and bug fix update

14 more advisories

Full record on NVD

Fix

  1. Update Linux linux kernel to 5.11.4 · 5.10.21 · 5.4.103 · 4.19.179 · 4.14.224 · 4.9.260 · 4.4.260
  2. Vendor fix Red Hat Product Security RHSA-2021:1531 · 120 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect.
  3. Vendor fix Red Hat Product Security RHSA-2021:1532 · 55 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  4. Workaround from the vendor Red Hat Product Security RHSA-2021:1531 · 120 productsThe LIBISCSI module will be auto-loaded when required, its use can be disabled by preventing the module from loading with the following instructions: ~~~ # echo "install libiscsi /bin/true" >> /etc/modprobe.d/disable-libiscsi.conf ~~~ The system will need to be restarted if the libiscsi modules ar…

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2021-03-07
Last Modified
2026-07-30
NVD status
Analyzed
GitHub Advisory
GHSA-qwp9-8pwv-6hg4

Frequently asked questions

What is CVE-2021-27365?

An issue was discovered in the Linux kernel through 5.11.3. Certain iSCSI data structures do not have appropriate length constraints or checks, and can exceed the PAGE_SIZE value. An unprivileged user can send a Netlink message that is associated with iSCSI, and has a length up to the maximum length of a Netlink message.

Is CVE-2021-27365 actively exploited?

Active exploitation of CVE-2021-27365 has not been confirmed. Its EPSS score was 2.1% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-27365?

CVE-2021-27365 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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