Page generated: 11 Nov 2026, 09:54 UTC
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CVE-2020-35730

An XSS issue was discovered in Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, and 1.4.x before 1.4.10. The attacker can send a plain text e-mail message, with JavaScript in a link reference element that is mishandled by linkref_addindex in rcube_string_replacer.php.

CVSS 6.1 (MEDIUM) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.1/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 6.1: +0.91
  • Fresh EPSS: 32.92%: +0.16

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

Sources: 10 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

Help Net Security
Press · 13 Feb 2024, 08:00 · Roundcube webmail XSS vulnerability exploited by attackers (CVE-2023-43770) - Help Net Security
BleepingComputer
Press · 12 Feb 2024, 08:00 · CISA: Roundcube email server bug now exploited in attacks - BleepingComputer
Help Net Security
Press · 25 Oct 2023, 07:00 · Roundcube webmail zero-day exploited to spy on government entities (CVE-2023-5631) - Help Net Security
The Record from Recorded Future News
Press · 25 Oct 2023, 07:00 · Espionage group uses webmail server zero-day to target European governments - The Record from Recorded Future News
WeLiveSecurity
Press · 25 Oct 2023, 07:00 · Winter Vivern exploits zero-day vulnerability in Roundcube Webmail servers - WeLiveSecurity
See all 10 source documents
CyberSecurityNews
Press · 19 Jul 2023, 07:00 · Hackers Exploit Zimbra and Roundcube Email Servers to Attack Government Organizations - CyberSecurityNews
Check Point Research
Press · 03 Jul 2023, 07:00 · 3rd July – Threat Intelligence Report - Check Point Research
SOC Prime
Press · 21 Jun 2023, 07:00 · CVE-2020-35730, CVE-2021-44026, CVE-2020-12641 Exploit Detection: APT28 Group Abuses Roundcube Flaws In Spearphishing Espionage Attacks - SOC Prime
Bitdefender
Press · 21 Jun 2023, 07:00 · Russian APT Group Exposes Vulnerabilities in Open-Source Roundcube Webmail Software - Bitdefender
Recorded Future
Press · 20 Jun 2023, 07:00 · BlueDelta Exploits Ukrainian Government Roundcube Mail Servers to Support Espionage Activities - Recorded Future

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 8.1 (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
skyllpro/CVE-2021-44026-PoC00Python20 Apr 2025, 07:32
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 6.1; EPSS 32.9%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
network access, no prior privileges, user interaction.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:58:18.514971+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
28 Dec 2020, 19:37
First press mention
20 Jun 2023, 07:00
Added to the CISA KEV catalog
22 Jun 2023, 00:00
Latest press mention
13 Feb 2024, 08:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
1 repositories