Page generated: 08 Nov 2026, 13:51 UTC
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CVE-2021-39144

XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user is affected, who followed the…

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XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
CVSS 8.5 (HIGH) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.8/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 8.5: +1.27
  • Fresh EPSS: 98.12%: +0.49

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

BleepingComputer
Press · 11 Mar 2023, 08:00 · CISA warns of actively exploited Plex bug after LastPass breach - BleepingComputer
The Register
Press · 26 Oct 2022, 07:00 · Cisco AnyConnect Windows client under active attack - The Register
BleepingComputer
Press · 25 Oct 2022, 07:00 · VMware fixes critical Cloud Foundation remote code execution bug - BleepingComputer

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 8.8 (2026-11-02 15:12). The curve appears once the score changes.

Public exploit evidence

0

Public exploit entries / repo candidates

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 8.5; EPSS 98.1%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
network access, low 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 13:58:30.019134+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
23 Aug 2021, 00:00
First press mention
25 Oct 2022, 07:00
Added to the CISA KEV catalog
10 Mar 2023, 00:00
Latest press mention
11 Mar 2023, 08:00
Score calculated
05 Nov 2026, 13:58