Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | https://github.com/curl/curl | curl 7.7 to and including 7.77.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | curl | 7.68.0-1ubuntu2.6 | USN-5021-1 |
| Ubuntu 18.04 LTS | curl | 7.58.0-2ubuntu3.14 | USN-5021-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | curl | 7.47.0-1ubuntu2.19+esm3 | USN-5894-1, USN-5021-2 |
| Ubuntu Pro 14.04 LTS | curl | 7.35.0-1ubuntu2.20+esm14 | USN-5894-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | curl +3 | 7.61.1-22.el8 | RHSA-2021:4511 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 8 | curl +3 | 7.61.1-22.el8 | ALSA-2021:4511 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | curl | 7.61.1-22.el8 | RLSA-2021:4511 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP3 | curl | 7.66.0-4.22.1 | SUSE-SU-2021:2439-1 |
| SLES 15 SP2 | curl | 7.66.0-4.22.1 | SUSE-SU-2021:2439-1 |
| SLES 15 SP1 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SLES 15 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SLES 12 SP5 | curl | 7.60.0-11.23.1 | SUSE-SU-2021:2462-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP4 | curl | 7.60.0-4.25.1 | SUSE-SU-2021:2425-1 |
| SLES 11 | curl-openssl1 | 7.37.0-70.71.1 | SUSE-SU-2021:14768-1 |
| SLES for SAP 15 SP1 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SLES for SAP 15 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SLES for SAP 12 SP5 | curl | 7.60.0-11.23.1 | SUSE-SU-2021:2462-1 |
| SLES for SAP 12 SP4 | curl | 7.60.0-4.25.1 | SUSE-SU-2021:2425-1 |
| SLE Micro 5.0 | curl | 7.66.0-4.22.1 | SUSE-SU-2021:2439-1 |
| SLE HPC 15 SP1 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SLE HPC 15 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SUSE OpenStack Cloud Crowbar 9 | curl | 7.60.0-4.25.1 | SUSE-SU-2021:2425-1 |
| SUSE OpenStack Cloud 9 | curl | 7.60.0-4.25.1 | SUSE-SU-2021:2425-1 |
| SUSE Manager Server 4.0 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SUSE Manager Retail Branch Server 4.0 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SUSE Manager Proxy 4.0 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
| SUSE Enterprise Storage 6 | curl | 7.60.0-3.47.1 | SUSE-SU-2021:2440-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.3 | curl | 7.66.0-4.22.1 | openSUSE-SU-2021:2439-1 |
| openSUSE Leap 15.2 | curl +1 | 7.66.0-lp152.3.21.1 | openSUSE-SU-2021:1088-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | curl | 7.78.0-r0 | — |
| Alpine v3.23 | curl | 7.78.0-r0 | — |
| Alpine v3.22 | curl | 7.78.0-r0 | — |
| Alpine v3.21 | curl | 7.78.0-r0 | — |
| Alpine v3.20 | curl | 7.78.0-r0 | — |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | curl | 7.78.0-r0 | — |
| Alpine v3.18 | curl | 7.78.0-r0 | — |
| Alpine v3.17 | curl | 7.78.0-r0 | — |
| Alpine v3.16 | curl | 7.78.0-r0 | — |
| Alpine v3.15 | curl | 7.78.0-r0 | — |
| Alpine v3.14 | curl | 7.78.0-r0 | — |
| Alpine v3.13 | curl | 7.78.0-r0 | — |
| Alpine v3.12 | curl | 7.78.0-r0 | — |
| Alpine v3.11 | curl | 7.67.0-r5 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | curl +2 | 7.76.1-7.amzn2.0.2 | ALAS2-2021-1700 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | curl | 7.76.0-5 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | curl +3 | 7.61.1-22.el8 | ELSA-2021-4511 |
Advisories 26
- ALSA-2021:4511 Moderate: curl security and bug fix update AlmaLinux Security Advisories · Oct 29, 2026
- SSA-398330 SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5 Siemens ProductCERT · Oct 13, 2026
- RHSA-2021:4511 Red Hat Security Advisory: curl security and bug fix update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- WID-SEC-2023-1350 Splunk Splunk Enterprise: Mehrere Schwachstellen in Komponenten von Drittanbietern BSI CERT-Bund (WID) · Jul 1, 2026
- USN-5894-1 curl vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
- USN-5021-2 curl vulnerability Ubuntu Security Notices (USN) · Jun 25, 2026
- USN-5021-1 curl vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- RLSA-2021:4511 Moderate: curl security and bug fix update Rocky Linux Security Advisories · Feb 4, 2026
- SUSE-SU-2021:2462-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:14768-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2440-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2439-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2425-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1088-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2026-0180 Dell Data Protection Advisor: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 20, 2026
- WID-SEC-2023-2229 Splunk Splunk Enterprise: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 18, 2025
- ALAS2-2021-1700 Moderate: curl security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 23, 2025
- ICSA-23-348-10 Siemens SIMATIC S7-1500 CISA ICS & IT advisories · Aug 12, 2025
- VDE-2022-010 PHOENIX CONTACT: Multiple Linux component vulnerabilities fixed in latest AXC F x152 LTS release CERT@VDE · May 22, 2025
- openSUSE-SU-2021:2439-1 Security update for curl SUSE / openSUSE Security Updates · May 7, 2025
- ICSA-22-069-09 Siemens SINEC INS CISA ICS & IT advisories · May 6, 2025
- ICSA-22-167-17 Siemens OpenSSL Affecting Industrial Products CISA ICS & IT advisories · Jul 9, 2024
- SSA-484086 SSA-484086: Multiple Vulnerabilities in SINEMA Remote Connect Server before V3.1 Siemens ProductCERT · Jul 9, 2024
- WID-SEC-2022-0874 cURL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 4, 2023
- SSA-389290 SSA-389290: Third-Party Component Vulnerabilities in SINEC INS Siemens ProductCERT · Mar 8, 2022
- ELSA-2021-4511 Moderate: curl security and bug fix update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Nov 16, 2021
References
- https://hackerone.com/reports/1223882
- FEDORA-2021-5d21b90a30 vendor-advisory
- 20210921 APPLE-SA-2021-09-20-8 Additional information for APPLE-SA-2021-09-13-4 Security Update 2021-005 Catalina mailing-list
- 20210921 APPLE-SA-2021-09-20-7 Additional information for APPLE-SA-2021-09-13-3 macOS Big Sur 11.6 mailing-list
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://security.netapp.com/advisory/ntap-20210902-0003/
- https://support.apple.com/kb/HT212805
- https://support.apple.com/kb/HT212804
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf
- GLSA-202212-01 vendor-advisory