Description
curl 7.63.0 to and including 7.75.0 includes vulnerability that allows a malicious HTTPS proxy to MITM a connection due to bad handling of TLS 1.3 session tickets. When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. When confusing the tickets, a HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed. Note that such a malicious HTTPS proxy needs to provide a certificate that curl will accept for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | https://github.com/curl/curl | 7.63.0 to and including 7.75.0 | — |
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.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | curl | 7.74.0-1.2 | — |
| Debian 13 | curl | 7.74.0-1.2 | — |
| Debian 12 | curl | 7.74.0-1.2 | — |
| Debian 10 | curl | 7.64.0-4+deb10u2 | DSA-4881-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | curl | 7.68.0-1ubuntu2.5 | USN-4898-1 |
| Ubuntu 18.04 LTS | curl | 7.58.0-2ubuntu3.13 | USN-4898-1 |
| Ubuntu 16.04 LTS | curl | 7.47.0-1ubuntu2.19 | USN-4898-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat JBoss Core Services 1 | jbcs-httpd24 +1 | 1-18.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-apr +1 | 1.6.3-105.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-apr-util +8 | 1.6.1-82.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-brotli +1 | 1.0.6-40.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-curl +2 | 7.77.0-2.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-httpd +6 | 2.4.37-74.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-jansson +1 | 2.11-55.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_cluster-native | 1.3.16-5.Final_redhat_2.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_http2 | 1.15.7-17.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_jk +2 | 1.2.48-16.redhat_1.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_md | 1:2.0.8-36.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_security | 2.9.2-63.GA.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_ssl +1 | 1:2.4.37-74.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-nghttp2 +1 | 1.39.2-37.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl +4 | 1:1.1.1g-6.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-chil | 1.0.0-5.el8jbcs | RHSA-2021:2472 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-pkcs11 | 0.4.10-20.el8jbcs | RHSA-2021:2472 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | curl | 7.66.0-4.14.1 | SUSE-SU-2021:1006-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLE Micro 5.0 | curl | 7.66.0-4.14.1 | SUSE-SU-2021:1006-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | curl | 7.79.1-1.1 | openSUSE-SU-2024:10582-1 |
| openSUSE Leap 15.2 | curl +1 | 7.66.0-lp152.3.15.1 | openSUSE-SU-2021:0510-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | curl | 7.76.0-r0 | — |
| Alpine v3.23 | curl | 7.76.0-r0 | — |
| Alpine v3.22 | curl | 7.76.0-r0 | — |
| Alpine v3.21 | curl | 7.76.0-r0 | — |
| Alpine v3.20 | curl | 7.76.0-r0 | — |
Show 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | curl | 7.76.0-r0 | — |
| Alpine v3.18 | curl | 7.76.0-r0 | — |
| Alpine v3.17 | curl | 7.76.0-r0 | — |
| Alpine v3.16 | curl | 7.76.0-r0 | — |
| Alpine v3.15 | curl | 7.76.0-r0 | — |
| Alpine v3.14 | curl | 7.76.0-r0 | — |
| Alpine v3.13 | curl | 7.76.0-r0 | — |
| Alpine v3.12 | curl | 7.76.0-r0 | — |
Advisories 13
- RHSA-2021:2472 Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.37 SP8 security update Red Hat Security Advisories (RHSA) · Oct 15, 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
- WID-SEC-2023-1350 Splunk Splunk Enterprise: Mehrere Schwachstellen in Komponenten von Drittanbietern BSI CERT-Bund (WID) · Jul 1, 2026
- USN-4898-1 curl vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-4881-1 curl - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10582-1 curl-7.79.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:0510-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:1006-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-2229 Splunk Splunk Enterprise: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 18, 2025
- WID-SEC-2023-1634 cURL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 6, 2025
- ICSA-23-348-10 Siemens SIMATIC S7-1500 CISA ICS & IT advisories · Aug 12, 2025
- ICSA-22-069-09 Siemens SINEC INS CISA ICS & IT advisories · May 6, 2025
- SSA-389290 SSA-389290: Third-Party Component Vulnerabilities in SINEC INS Siemens ProductCERT · Mar 8, 2022
References
- https://hackerone.com/reports/1129529
- https://curl.se/docs/CVE-2021-22890.html
- FEDORA-2021-cab5c9befb vendor-advisory
- FEDORA-2021-065371f385 vendor-advisory
- FEDORA-2021-26a293c72b vendor-advisory
- GLSA-202105-36 vendor-advisory
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://security.netapp.com/advisory/ntap-20210521-0007/
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf