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CVE-2022-4891

25
FAUCET Score

CVE-2022-4891 is a problematic vulnerability affecting Sisimai versions up to 4.25.14p11, specifically within the to_plain function of lib/sisimai/string.rb. This flaw, categorized as inefficient regular expression complexity (CWE-1333), allows for a denial-of-service attack. With a CVSS score of 7.5 (High), it can be exploited remotely with low attack complexity and no user interaction, leading to high availability impact. While the exploit has been publicly disclosed, there is no evidence of active exploitation, nor are there Metasploit, Nuclei, or ExploitDB modules available, and community discussion remains minimal.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.25.14CPE matchmatch criteria
cpe:2.3:a:libsisimai:sisimai:*:*:*:*:*:*:*:*
4.25.14CPE matchmatch criteria
cpe:2.3:a:libsisimai:sisimai:4.25.14:-:*:*:*:*:*:*
4.25.14CPE matchmatch criteria
cpe:2.3:a:libsisimai:sisimai:4.25.14:p1:*:*:*:*:*:*
4.25.14CPE matchmatch criteria
cpe:2.3:a:libsisimai:sisimai:4.25.14:p10:*:*:*:*:*:*
4.25.14CPE matchmatch criteria
cpe:2.3:a:libsisimai:sisimai:4.25.14:p11:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

3.5LOW

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.1
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.34%
Probability of exploitation in next 30 days
EPSS Percentile
68.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0134 is in the 48th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
rubygemspatch availablevia ghsa
Product: sisimaiFixed in: 4.25.14p12

Vendor Advisories (1)

rubygemsGHSA-vm74-j4wq-82xjmedium

Sisimai Inefficient Regular Expression Complexity vulnerability

Jan 17, 2023

References

gist.githubusercontent.com / gmcabrita/e5dc0332473fc2e3a7a407434c8d21c7/raw/00b12035e5e1b685469f143b94301a50306376ba/example.html
ExploitThird Party Advisory
github.com / sisimai/rb-sisimai/commit/51fe2e6521c9c02b421b383943dc9e4bbbe65d4e
PatchThird Party Advisory
github.com / sisimai/rb-sisimai/pull/244
ExploitPatchThird Party Advisory
github.com / sisimai/rb-sisimai/releases/tag/v4.25.14p12
Release NotesThird Party Advisory
vuldb.com
Permissions RequiredThird Party Advisory
vuldb.com
Permissions RequiredThird Party Advisory