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CVE-2021-22555

96
FAUCET Score

CVE-2021-22555 is a heap out-of-bounds write vulnerability in the Linux kernel's netfilter x_tables component, affecting Linux since version 2.6.19-rc1, as well as products from Brocade and NetApp. It carries a high CVSS score of 7.8, indicating that a local attacker with low privileges can achieve privilege escalation or cause a denial of service with low attack complexity. This vulnerability is actively exploited in the wild, with public exploit code available (e.g., Metasploit, ExploitDB), and has garnered significant community discussion and media coverage, highlighting its critical nature.

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:netapp:c400_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.3HIGH

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Attack Vector
ADJACENT_NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.6
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
78.68%
Probability of exploitation in next 30 days
EPSS Percentile
99.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Added to KEV · Oct 6, 2025
Metasploit: Netfilter x_tables Heap OOB Write Privilege Escalation · Jul 7, 2021
ExploitDB: EDB-50135 · Jul 15, 2021
This CVE's current EPSS score of 0.7868 is in the 100th percentile among its peer group of 17,070 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (27)

boschpatch availablevia llm_extracted
View patch
mongodbpatch availablevia llm_extracted
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: kernel-0:3.10.0-1160.41.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: kpatch-patch
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.2 Advanced Update SupportFixed in: kernel-0:3.10.0-327.100.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.3 Advanced Update SupportFixed in: kernel-0:3.10.0-514.92.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.4 Advanced Update SupportFixed in: kernel-0:3.10.0-693.94.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.6 Advanced Update Support(Disable again in 2026 - SPRHEL-7118)Fixed in: kernel-0:3.10.0-957.84.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.6 Telco Extended Update SupportFixed in: kernel-0:3.10.0-957.84.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.6 Update Services for SAP SolutionsFixed in: kernel-0:3.10.0-957.84.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.6 Update Services for SAP SolutionsFixed in: kpatch-patch
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.7 Advanced Update SupportFixed in: kernel-0:3.10.0-1062.56.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.7 Telco Extended Update SupportFixed in: kernel-0:3.10.0-1062.56.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONFixed in: kernel-0:2.6.32-754.58.1.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.7 Update Services for SAP SolutionsFixed in: kpatch-patch
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-rt-0:4.18.0-305.12.1.rt7.84.el8_4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kpatch-patch
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-0:4.18.0-305.12.1.el8_4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Extended Update SupportFixed in: kernel-0:4.18.0-147.52.1.el8_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Extended Update SupportFixed in: kpatch-patch
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.2 Extended Update SupportFixed in: kernel-rt-0:4.18.0-193.64.1.rt13.115.el8_2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.2 Extended Update SupportFixed in: kernel-0:4.18.0-193.64.1.el8_2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.2 Extended Update SupportFixed in: kpatch-patch
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Virtualization 4 for Red Hat Enterprise Linux 7Fixed in: redhat-virtualization-host-0:4.3.18-20210903.0.el7_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Virtualization 4 for Red Hat Enterprise Linux 8Fixed in: redhat-virtualization-host-0:4.4.7-20210804.0.el8_4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.7 Update Services for SAP SolutionsFixed in: kernel-0:3.10.0-1062.56.1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: kernel-rt-0:3.10.0-1160.41.1.rt56.1181.el7
View patch

Vendor Advisories (4)

linuxCVE-2021-22555HIGH

A heap out-of-bounds write affecting Linux since v2.6.19-rc1 was discovered in net/netfilter/x_tables.c. This allows an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space

Jul 7, 2021
redhatCVE-2021-22555Important

kernel: out-of-bounds write in xt_compat_target_from_user() in net/netfilter/x_tables.c

Jul 7, 2021
boschllm-bosch-d99e7d22329dfa30HIGH

Runc container breakout vulnerability (CVE-2021-22555)

mongodbllm-mongodb-ca499e5d36d6c4b3HIGH

runc container breakout vulnerability (CVE-2021-22555)

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
packetstormsecurity.com / files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.html
Third Party AdvisoryVDB Entry
packetstormsecurity.com / files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.html
ExploitThird Party AdvisoryVDB Entry
packetstormsecurity.com / files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html
ExploitThird Party AdvisoryVDB Entry
packetstormsecurity.com / files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.html
ExploitThird Party AdvisoryVDB Entry
packetstormsecurity.com / files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html
ExploitThird Party AdvisoryVDB Entry
github.com / google/security-research/security/advisories/GHSA-xxx5-8mvq-3528
ExploitThird Party Advisory
git.kernel.org / pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c
Mailing ListPatchVendor Advisory
git.kernel.org / pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c
Mailing ListPatchVendor Advisory
security.netapp.com / advisory/ntap-20210805-0010
Third Party Advisory