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NVD / CVE Program· CNA hackerone

CVE-2021-22946: A user can tell curl >= 7.20.0 and <= 7.78.0 to require a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server…

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 4.5% (FIRST EPSS); higher than 91.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: curl (Alpine:v3.11) 7.79.0-r0; curl (Debian:10) 7.64.0-4+deb10u3; curl (Debian:11) 7.74.0-1.3+deb11u2.
  • Mentioned 6 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to curl (Alpine:v3.11) 7.79.0-r0; curl (Debian:10) 7.64.0-4+deb10u3; curl (Debian:11) 7.74.0-1.3+deb11u2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A user can tell curl >= 7.20.0 and <= 7.78.0 to require a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server (`--ssl-reqd` on the command line or`CURLOPT_USE_SSL` set to `CURLUSESSL_CONTROL` or `CURLUSESSL_ALL` withlibcurl). This requirement could be bypassed if the server would return a properly crafted but perfectly legitimate response.This flaw would then make curl silently continue its operations **withoutTLS** contrary to the instructions and expectations, exposing possibly sensitive data in clear text over the network.

Published
Sep 29, 2021
Updated
Oct 14, 2026
EPSS
4.5% · 91th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.5%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.5
CNA · hackerone
7.5
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-22946

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
haxxcurl
debiandebian linux
fedoraprojectfedora
netappcloud backup
netappclustered data ontap
netapponcommand insight
netapponcommand workflow automation
netappsnapcenter
netapph300s firmware
netapph300s
netapph500s firmware
netapph500s

and 25 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apple macosbefore 12.3
  • debian debian linux10.0
  • debian debian linux11.0
  • debian debian linux9.0
  • fedoraproject fedora33
  • fedoraproject fedora35
  • haxx curl7.20.0 and later · before 7.79.0
  • netapp cloud backupall versions
  • netapp clustered data ontapall versions
  • netapp h300e firmwareall versions
  • netapp h300s firmwareall versions
  • netapp h410s firmwareall versions
  • netapp h500e firmwareall versions
  • netapp h500s firmwareall versions
  • netapp h700e firmwareall versions
  • netapp h700s firmwareall versions
  • netapp oncommand insightall versions
  • netapp oncommand workflow automationall versions
  • netapp snapcenterall versions
  • netapp solidfire baseboard management controller firmwareall versions

Versions reported by the vendor

Affected version ranges reported by the assigning authority (hackerone). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a https://github.com/curl/curl

    • curl 7.20.0 to and including 7.78.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.11curlfrom 7.20.0 · before 7.79.0-r07.79.0-r0
Debian:10curlbefore 7.64.0-4+deb10u37.64.0-4+deb10u3
Debian:11curlbefore 7.74.0-1.3+deb11u27.74.0-1.3+deb11u2
Debian:12curlbefore 7.79.1-17.79.1-1
Debian:9curlbefore 7.52.1-5+deb9u167.52.1-5+deb9u16
openSUSE:Leap 15.2curlbefore 7.66.0-lp152.3.24.17.66.0-lp152.3.24.1
openSUSE:Leap 15.2curl-minibefore 7.66.0-lp152.3.24.17.66.0-lp152.3.24.1
openSUSE:Leap 15.3curlbefore 7.66.0-4.27.17.66.0-4.27.1
Red Hat:enterprise_linux:8::baseoscurlbefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoscurl-debuginfobefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoscurl-debugsourcebefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoscurl-minimal-debuginfobefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoslibcurlbefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoslibcurl-debuginfobefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoslibcurl-develbefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoslibcurl-minimalbefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:enterprise_linux:8::baseoslibcurl-minimal-debuginfobefore 0:7.61.1-18.el8_4.20:7.61.1-18.el8_4.2
Red Hat:rhel_dotnet:3.1::el7rh-dotnet31-curlbefore 0:7.61.1-22.el7_90:7.61.1-22.el7_9
Red Hat:rhel_dotnet:3.1::el7rh-dotnet31-curl-debuginfobefore 0:7.61.1-22.el7_90:7.61.1-22.el7_9
Red Hat:rhel_dotnet:3.1::el7rh-dotnet31-libcurlbefore 0:7.61.1-22.el7_90:7.61.1-22.el7_9
Red Hat:rhel_dotnet:3.1::el7rh-dotnet31-libcurl-develbefore 0:7.61.1-22.el7_90:7.61.1-22.el7_9
Red Hat:rhel_eus:8.2::baseoscurlbefore 0:7.61.1-12.el8_2.40:7.61.1-12.el8_2.4
Red Hat:rhel_eus:8.2::baseoscurl-debuginfobefore 0:7.61.1-12.el8_2.40:7.61.1-12.el8_2.4
Red Hat:rhel_eus:8.2::baseoscurl-debugsourcebefore 0:7.61.1-12.el8_2.40:7.61.1-12.el8_2.4

+12

Same product

haxx: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-22901curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session…
    51Plan
  • CVE-2023-38039When curl retrieves an HTTP response, it stores the incoming headers so that they can be accessed later via the libcurl headers API.
    47Plan
  • CVE-2024-2398HTTP/2 push headers memory-leak
    45Plan

Published before and after this one in the same product

  • ← EarlierCVE-2021-22925Aug 5, 2021 · curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl.
    23Monitor
  • ← EarlierCVE-2021-22926Aug 5, 2021 · libcurl-using applications can ask for a specific client certificate to be used in a transfer.
    35Monitor
  • Later →CVE-2021-22947Sep 29, 2021 · When curl >= 7.20.0 and <= 7.78.0 connects to an IMAP or POP3 server to retrieve data using STARTTLS to upgrade to TLS security, the server…
    24Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:curl7.79.0-r0 · Alpine:v3.11Package registry (OSV)
debian:curl7.79.1-1 · Debian:12Package registry (OSV)
opensuse:curl7.66.0-lp152.3.24.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:curl-mini7.66.0-lp152.3.24.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:curl0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:curl-debuginfo0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:curl-debugsource0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:curl-minimal-debuginfo0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libcurl0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libcurl-debuginfo0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libcurl-devel0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libcurl-minimal0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:libcurl-minimal-debuginfo0:7.61.1-18.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:rh-dotnet31-curl0:7.61.1-22.el7_9 · Red Hat:rhel_dotnet:3.1::el7Package registry (OSV)
red hat:rh-dotnet31-curl-debuginfo0:7.61.1-22.el7_9 · Red Hat:rhel_dotnet:3.1::el7Package registry (OSV)
red hat:rh-dotnet31-libcurl0:7.61.1-22.el7_9 · Red Hat:rhel_dotnet:3.1::el7Package registry (OSV)
rocky linux:curl0:7.61.1-18.el8_4.2 · Rocky Linux:8Package registry (OSV)
suse:curl7.60.0-25.1 · SUSE:Linux Enterprise High Performance Computing 15-ESPOSPackage registry (OSV)
suse:curl-openssl17.37.0-70.74.1 · SUSE:Linux Enterprise Server 11-SECURITYPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-325 · Missing Cryptographic Step

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (17 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records