Exploitation evidence
Known exploited · CISA KEV listed
Added 2025-10-06. Ransomware campaign use: Unknown.
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA due date: 2025-10-27. This is the catalog’s deadline, not an assessment of your organization’s exposure.
KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗Reported products and versions
n/a / Linux Kernel
Default status: Not specified
- affected: 2.6.19-rc1 to < unspecified (custom)
Fixes and workarounds
No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.
Sources and related reporting
CVE Program record ↗ · Download tracked evidence as JSON
- https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d
- http://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.html
- https://security.netapp.com/advisory/ntap-20210805-0010/
- http://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.html
- http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html
- http://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.html
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22555
Observed change timeline
History begins when Egret first downloads each source. It is not the complete upstream CVE history.
12 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-12",
"epss": 0.78684,
"percentile": 0.99595
}10 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.78684,
"percentile": 0.99592
}09 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-09",
"epss": 0.78684,
"percentile": 0.99591
}08 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-08",
"epss": 0.78684,
"percentile": 0.99591
}07 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-07",
"epss": 0.78684,
"percentile": 0.99591
}06 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-06",
"epss": 0.78684,
"percentile": 0.9959
}06 Nov 2026, 06:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-05",
"epss": 0.78684,
"percentile": 0.9959
}06 Nov 2026, 00:20 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
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}04 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-04",
"epss": 0.78684,
"percentile": 0.99589
}03 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
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"epss": 0.78684,
"percentile": 0.99589
}03 Nov 2026, 02:22 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-02",
"epss": 0.78684,
"percentile": 0.99588
}03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed
Stored KEV snapshot at this observation.
{
"cveID": "CVE-2021-22555",
"cwes": [
"CWE-787"
],
"dateAdded": "2025-10-06",
"dueDate": "2025-10-27",
"forensicTriage": "No",
"knownRansomwareCampaignUse": "Unknown",
"notes": "https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=9fa492cdc160cd27ce1046cb36f47d3b2b1efa21 ; https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter/x_tables.c?id=b29c457a6511435960115c0f548c4360d5f4801d ; https://security.netapp.com/advisory/ntap-20210805-0010/ ; https://github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528 ; https://nvd.nist.gov/vuln/detail/CVE-2021-22555",
"product": "Kernel",
"requiredAction": "Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.",
"shortDescription": "Linux Kernel contains a heap out-of-bounds write vulnerability that could allow an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space.",
"vendorProject": "Linux",
"vulnerabilityName": "Linux Kernel Heap Out-of-Bounds Write Vulnerability"
}