curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl.
curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl. This rarely used option is used to send variable=content pairs toTELNET servers.Due to flaw in the option parser for sending `NEW_ENV` variables, libcurlcould be made to pass on uninitialized data from a stack based buffer to theserver. Therefore potentially revealing sensitive internal information to theserver using a clear-text network protocol.This could happen because curl did not call and use sscanf() correctly whenparsing the string provided by the application.
- Published
- Aug 5, 2021
- Updated
- Jun 16, 2026
- EPSS
- 4.9% · 92th percentile
- CWE
- CWE-200
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Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 4.9%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| haxx | curl | cpe:2.3:a:haxx:curl |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| netapp | cloud backup | cpe:2.3:a:netapp:cloud_backup |
| netapp | clustered data ontap | cpe:2.3:a:netapp:clustered_data_ontap |
| netapp | hci management node | cpe:2.3:a:netapp:hci_management_node |
| netapp | solidfire | cpe:2.3:a:netapp:solidfire |
| apple | mac os x | cpe:2.3:o:apple:mac_os_x |
| apple | macos | cpe:2.3:o:apple:macos |
| oracle | mysql server | cpe:2.3:a:oracle:mysql_server |
| oracle | peoplesoft enterprise peopletools | cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools |
| siemens | sinec infrastructure network services | cpe:2.3:a:siemens:sinec_infrastructure_network_services |
| siemens | sinema remote connect server | cpe:2.3:a:siemens:sinema_remote_connect_server |
and 15 more
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- oracle mysql server5.7.0 and later · up to 5.7.35 inclusive
- oracle mysql server8.0.0 and later · up to 8.0.26 inclusive
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 7.7 to and including 7.77.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | curl | before 7.61.1-22.el8 | 7.61.1-22.el8 |
| AlmaLinux:8 | libcurl | before 7.61.1-22.el8 | 7.61.1-22.el8 |
| AlmaLinux:8 | libcurl-devel | before 7.61.1-22.el8 | 7.61.1-22.el8 |
| AlmaLinux:8 | libcurl-minimal | before 7.61.1-22.el8 | 7.61.1-22.el8 |
| Alpine:v3.11 | curl | from 7.7 · before 7.67.0-r5 | 7.67.0-r5 |
| Alpine:v3.12 | curl | from 7.7 · before 7.78.0-r0 | 7.78.0-r0 |
| openSUSE:Leap 15.2 | curl | before 7.66.0-lp152.3.21.1 | 7.66.0-lp152.3.21.1 |
| openSUSE:Leap 15.2 | curl-mini | before 7.66.0-lp152.3.21.1 | 7.66.0-lp152.3.21.1 |
| openSUSE:Leap 15.3 | curl | before 7.66.0-4.22.1 | 7.66.0-4.22.1 |
| Red Hat:enterprise_linux:8::baseos | curl | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | curl-debuginfo | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | curl-debugsource | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | curl-minimal-debuginfo | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | libcurl | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | libcurl-debuginfo | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | libcurl-devel | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | libcurl-minimal | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Red Hat:enterprise_linux:8::baseos | libcurl-minimal-debuginfo | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| Rocky Linux:8 | curl | before 0:7.61.1-22.el8 | 0:7.61.1-22.el8 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | curl | before 7.60.0-3.47.1 | 7.60.0-3.47.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP2 | curl | before 7.66.0-4.22.1 | 7.66.0-4.22.1 |
| SUSE:Linux Enterprise Server 11-SECURITY | curl-openssl1 | before 7.37.0-70.71.1 | 7.37.0-70.71.1 |
| SUSE:Linux Enterprise Software Development Kit 12 SP5 | curl | before 7.60.0-11.23.1 | 7.60.0-11.23.1 |
| SUSE:OpenStack Cloud 9 | curl | before 7.60.0-4.25.1 | 7.60.0-4.25.1 |
Same product
haxx: all recordsOther 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 t50Plan
- 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-leak45Plan
- CVE-2019-5482Heap buffer overflow in the TFTP protocol handler in cURL 7.19.4 to 7.65.3.44Plan
- CVE-2017-8817The FTP wildcard function in curl and libcurl before 7.57.0 allows remote attackers to cause a denial of service (out-of-bounds read and app42Plan
- CVE-2017-8816The NTLM authentication feature in curl and libcurl before 7.57.0 on 32-bit platforms allows attackers to cause a denial of service (integer42Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:curl | 7.61.1-22.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libcurl | 7.61.1-22.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libcurl-devel | 7.61.1-22.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libcurl-minimal | 7.61.1-22.el8 · AlmaLinux:8 | Package registry (OSV) |
| alpine:curl | 7.67.0-r5 · Alpine:v3.11 | Package registry (OSV) |
| opensuse:curl | 7.66.0-lp152.3.21.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| opensuse:curl-mini | 7.66.0-lp152.3.21.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| red hat:curl | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:curl-debuginfo | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:curl-debugsource | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:curl-minimal-debuginfo | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:libcurl | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:libcurl-debuginfo | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:libcurl-devel | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:libcurl-minimal | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| red hat:libcurl-minimal-debuginfo | 0:7.61.1-22.el8 · Red Hat:enterprise_linux:8::baseos | Package registry (OSV) |
| rocky linux:curl | 0:7.61.1-22.el8 · Rocky Linux:8 | Package registry (OSV) |
| suse:curl | 7.60.0-4.25.1 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:curl-openssl1 | 7.37.0-70.71.1 · SUSE:Linux Enterprise Server 11-SECURITY | Package 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.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
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 researchersFinders, 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.
- TR-23-0118 · Mar 1, 2023(Curl Güvenlik Güncellemesi)
- TR-22-0222 · Mar 15, 2022(RedHat Güvenlik Güncellemesi)
- TR-22-0215 · Mar 11, 2022(Siemens Güvenlik Bildirimi)
- TR-22-0113 · Feb 4, 2022(RedHat Güvenlik Güncellemesi)
- TR-22-0097 · Jan 28, 2022(RedHat Güvenlik Güncellemesi)
- TR-21-0963 · Dec 2, 2021(RedHat Güvenlik Güncellemesi)
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
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-200 · Exposure of Sensitive Information to an Unauthorized ActorCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
nvd-primary
Root cause
The extension requests broader permissions than its function needs and sends the data it collects out for purposes beyond its stated function.
The bug in code
The whole CWE-200 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
{ "permissions": ["tabs", "<all_urls>"], "background": { "service_worker": "analytics.js" }}Fixed
{ "permissions": ["activeTab"], "host_permissions": ["https://yildiz.example/*"]}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- ExcavationCAPEC-116likelihood: High · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
- FootprintingCAPEC-169likelihood: High · Very Low
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- FingerprintingCAPEC-224likelihood: High · Very Low
- ICMP Echo Request PingCAPEC-285likelihood: Medium · Low
- TCP SYN ScanCAPEC-287Low
- Enumerate Mail Exchange (MX) RecordsCAPEC-290Low
ATT&CK techniques
- System Service DiscoveryT1007
- System Network Configuration DiscoveryT1016
- Remote System DiscoveryT1018
- System Owner/User DiscoveryT1033
- Masquerading: Match Legitimate Name or LocationT1036.005
- Network Service ScanningT1046
- System Network Connections DiscoveryT1049
- Process DiscoveryT1057
- Permission Groups DiscoveryT1069
- System Information DiscoveryT1082
- File and Directory DiscoveryT1083
- Account DiscoveryT1087
- Multi-Factor Authentication InterceptionT1111
- Peripheral Device DiscoveryT1120
- System Time DiscoveryT1124
- Access Token Manipulation:Token Impersonation/TheftT1134.001
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- seclists.org/fulldisclosure/2021/Sep/39
- seclists.org/fulldisclosure/2021/Sep/40
- cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FRUCW2UVNYUDZF72DQLFQR4PJEC6CF7V/
- security.gentoo.org/glsa/202212-01
- security.netapp.com/advisory/ntap-20210902-0003/
- support.apple.com/kb/HT212804
- support.apple.com/kb/HT212805
- www.oracle.com/security-alerts/cpujan2022.html
- www.oracle.com/security-alerts/cpuoct2021.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.