CVE-2021-22555

Exploitation

Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2025-10-06. Federal remediation due 2025-10-27.

SSVC decision

• ExploitationactiveCISA reports credible evidence of active exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

78.68% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 99.6% of scored records. A rank, not a probability.

NVD base score

7.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-07-07 11:20Z5 YR AGO

Last updated

2025-12-30 20:32Z8 MO AGO

Reserved

2021-01-05

Assigning CNA

Google

Record state

PUBLISHED

Severity

High (CVSS 8.3)

CNA CVSS vector

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

Weaknesses

• CWE-787Out-of-bounds WriteBase

Data version

5.2

Document digest

e091febae3b7cfe556d6635d0c800023b91c7f32cac127cbddd9bef6fe28911b

• github.comhttps://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528x_refsource_MISC
• git.kernel.orghttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21x_refsource_MISC
• git.kernel.orghttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801dx_refsource_MISC
• packetstormsecurity.comhttp://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.htmlx_refsource_MISC
• security.netapp.comhttps://security.netapp.com/advisory/ntap-20210805-0010/x_refsource_CONFIRM
• packetstormsecurity.comhttp://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.htmlx_refsource_MISC
• packetstormsecurity.comhttp://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlx_refsource_MISC
• packetstormsecurity.comhttp://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.htmlx_refsource_MISC
• packetstormsecurity.comhttp://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlx_refsource_MISC
• www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22555government-resource