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Fencer Vulns
high 7.5

CVE-2021-27293 json

Incorrect Regular Expression in RestSharp

published 2021-07-12 5 y ago modified 2026-06-17 4 mo ago also GHSA-9pq7-rcxv-47vq , EUVD-2021-1455

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

RestSharp < 106.11.8-alpha.0.13 uses a regular expression which is vulnerable to Regular Expression Denial of Service (ReDoS) when converting strings into DateTimes. If a server responds with a malicious string, the client using RestSharp will be stuck processing it for an exceedingly long time. Thus the remote server can trigger Denial of Service.

Patch / fix

  • nuget RestSharp 106.11.8-alpha.0.13

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-27293 updated cvss 7.5

restsharp: ReDoS when converting strings into DateTimes

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.51% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/restsharp/RestSharp/issues/1556 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
nuget RestSharp
<106.11.8-alpha.0.13
106.11.8-alpha.0.13

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.