Page generated: 09 Nov 2026, 08:30 UTC
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CVE-2021-22555

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

CVSS 8.3 (HIGH) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.6/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 8.3: +1.25
  • Fresh EPSS: 78.68%: +0.39

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 3 documents and public datasets.

Hype components

Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100

Sources and documents

Securelist
Press · 06 Mar 2026, 08:00 · Vulnerability landscape in Q4 2025 - Securelist
Recorded Future
Press · 06 Nov 2025, 08:00 · October 2025 CVE Landscape: 32 High-Impact Vulnerabilities Demand Immediate Attention - Recorded Future
www.trendmicro.com
Press · 18 Mar 2024, 07:00 · Earth Krahang Exploits Intergovernmental Trust to Launch Cross-Government Attacks - www.trendmicro.com

Score evolution

● Hype   ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 0.0 · reality 8.6 (2026-11-02 15:12). The curve appears once the score changes.

Public exploit evidence

1

Public exploit entries / repo candidates

See 1 repos with metrics
RepositoryStarsForksLanguageUpdated
Spydomain/CVE-2021-22555-Poc11C15 Oct 2026, 10:13
Public exploit evidence
Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.

Evidence in context

Confidence in exploitation evidence
Exploitation recorded
Priority basis
Recorded exploitation; CVSS 8.3; EPSS 78.7%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
adjacent access, no prior privileges, no user interaction, additional attack conditions.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:58:23.782764+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
07 Jul 2021, 11:20
First press mention
18 Mar 2024, 07:00
Added to the CISA KEV catalog
06 Oct 2025, 00:00
Latest press mention
06 Mar 2026, 08:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
1 repositories