Answer in brief
CVE-2021-22555 records a High severity vulnerability in Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE. The current sources mark it as known exploited. The current feed maps n/a/Linux Kernel (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2021-22555 records a High severity vulnerability in Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE. The current sources mark it as known exploited. The current feed maps n/a/Linux Kernel (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps n/a/Linux Kernel (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| n/a/Linux Kernelgeneric | >=2.6.19-rc1 <unspecified | unspecified |
Published upstream
Jul 7, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Dec 30, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Oct 6, 2025
Evidence: source:kev:kev:kev:recordA 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
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps n/a/Linux Kernel (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| n/a/Linux Kernelgeneric | >=2.6.19-rc1 <unspecified | unspecified |
Published upstream
Jul 7, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Dec 30, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Oct 6, 2025
Evidence: source:kev:kev:kev:recordA 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
Quoted source text, attributed separately from HOL analysis.