CVE-2022-27781Public exploitNetwork attack vector

Application hang via cyclic certificate chain

Published Jun 1, 2022 · Updated May 27, 2026

Infinite loop in curl libcurl 7.34.0 through 7.83.0 allows remote attackers to hang NSS-backed applications via a malicious TLS server. In display_conn_info in lib/vtls/nss.c, CERT_FindCertIssuer repeatedly follows a cyclic issuer chain without bounding the certificate count. The application must use an NSS-built libcurl with CURLOPT_CERTINFO enabled; the command-line tool cannot reach this path, and the affected process remains stuck.

CVSS severity7.5
High
EPSS probability2.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in curl libcurl 7.34.0 through 7.83.0 allows remote attackers to hang NSS-backed applications via a malicious TLS server. In display_conn_info in lib/vtls/nss.c, CERT_FindCertIssuer repeatedly follows a cyclic issuer chain without bounding the certificate count. The application must use an NSS-built libcurl with CURLOPT_CERTINFO enabled; the command-line tool cannot reach this path, and the affected process remains stuck.

The record

CVE
CVE-2022-27781
Published
Jun 1, 2022
Updated
May 27, 2026
Vendor
curl
Product
curl
Classifications
CWE-400, CWE-835, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 1, 2022CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed in 7.83.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

curl · curlversion=Fixed in 7.83.1

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499Endpoint Denial of Service

Public exploit references

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Technologies

Your stack

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Your stack

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