Description
The URL percent-encoding decode function in libcurl before 7.51.0 is called `curl_easy_unescape`. Internally, even if this function would be made to allocate a unscape destination buffer larger than 2GB, it would return that new length in a signed 32 bit integer variable, thus the length would get either just truncated or both truncated and turned negative. That could then lead to libcurl writing outside of its heap based buffer.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| The Curl Project | curl | 7.51.0 | — |
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 | 7.51.0-1 | — |
| Debian 13 | curl | 7.51.0-1 | — |
| Debian 12 | curl | 7.51.0-1 | — |
| Debian 8 | curl | 7.38.0-4+deb8u5 | DSA-3705-1 |
| Debian 7 | curl | 7.26.0-1+wheezy17 | DLA-711-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | curl | 7.47.0-1ubuntu2.2 | USN-3123-1 |
| Ubuntu 14.04 LTS | curl | 7.35.0-1ubuntu2.10 | USN-3123-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 3 | httpd24-curl +2 | 7.61.1-1.el6 | RHSA-2018:3558 |
| RHEL 3 | httpd24-httpd +5 | 2.4.34-7.el6 | RHSA-2018:3558 |
| RHEL 3 | httpd24-mod_md | 2.4.34-7.el7 | RHSA-2018:3558 |
| RHEL 3 | httpd24-mod_ssl +1 | 1:2.4.34-7.el6 | RHSA-2018:3558 |
| RHEL 3 | httpd24-nghttp2 +2 | 1.7.1-7.el6 | RHSA-2018:3558 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP1 | curl | 7.37.0-31.1 | SUSE-SU-2016:2699-1 |
| SLES 11 SP4 | curl | 7.19.7-1.64.1 | SUSE-SU-2016:2714-1 |
| SLES 11 | curl-openssl1 | 7.19.7-1.64.1 | SUSE-SU-2016:2714-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Studio Onsite 1.3 | curl | 7.19.7-1.20.47.2 | SUSE-SU-2016:2700-1 |
| SLES for SAP 12 SP1 | curl | 7.37.0-31.1 | SUSE-SU-2016:2699-1 |
| SLES for SAP 11 SP4 | curl | 7.19.7-1.64.1 | SUSE-SU-2016:2714-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | curl | 7.51.0-1.1 | openSUSE-SU-2024:10303-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | curl | 7.51.0-r0 | — |
| Alpine v3.23 | curl | 7.51.0-r0 | — |
| Alpine v3.22 | curl | 7.51.0-r0 | — |
| Alpine v3.21 | curl | 7.51.0-r0 | — |
| Alpine v3.20 | curl | 7.51.0-r0 | — |
Show 18 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | curl | 7.51.0-r0 | — |
| Alpine v3.18 | curl | 7.51.0-r0 | — |
| Alpine v3.17 | curl | 7.51.0-r0 | — |
| Alpine v3.16 | curl | 7.51.0-r0 | — |
| Alpine v3.15 | curl | 7.51.0-r0 | — |
| Alpine v3.14 | curl | 7.51.0-r0 | — |
| Alpine v3.13 | curl | 7.51.0-r0 | — |
| Alpine v3.12 | curl | 7.51.0-r0 | — |
| Alpine v3.11 | curl | 7.51.0 | — |
| Alpine v3.10 | curl | 7.51.0-r0 | — |
| Alpine v3.9 | curl | 7.51.0-r0 | — |
| Alpine v3.8 | curl | 7.51.0 | — |
| Alpine v3.7 | curl | 7.51.0 | — |
| Alpine v3.6 | curl | 7.51.0 | — |
| Alpine v3.5 | curl | 7.51.0-r0 | — |
| Alpine v3.4 | curl | 7.51.0-r0 | — |
| Alpine v3.3 | curl | 7.49.1-r4 | — |
| Alpine v3.2 | curl | 7.49.1-r4 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | curl +2 | 7.29.0-51.0.1.el7 | ELSA-2019-4652 |
Advisories 11
- RHSA-2018:3558 Red Hat Security Advisory: httpd24 security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- USN-3123-1 curl vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-711-1 curl - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3705-1 curl - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2016:2699-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:2700-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10303-1 curl-7.51.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2026-0180 Dell Data Protection Advisor: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 20, 2026
- SUSE-SU-2016:2714-1 Security update for curl SUSE / openSUSE Security Updates · May 2, 2025
- WID-SEC-2023-1652 cURL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Dec 13, 2023
- ELSA-2019-4652 Important: curl security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · May 21, 2019
References
- RHSA-2018:3558 vendor-advisory
- https://curl.haxx.se/docs/adv_20161102H.html
- https://www.tenable.com/security/tns-2016-21
- 1037192 vdb-entry
- http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html
- 94105 vdb-entry
- RHSA-2018:2486 vendor-advisory
- GLSA-201701-47 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-8622