SB2026101540 - Debian update for curl
Published: October 15, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2026-92392)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use-after-free in curl's HTTP/2 upload handling when processing server-supplied stream resets during an upload. A remote attacker can send specially crafted HTTP/2 RST_STREAM frames with the HTTP_1_1_REQUIRED or REFUSED_STREAM reason to execute arbitrary code.
The demonstrated exploitation requires knowledge of the exact curl object layout, target architecture, compatible libc allocator and heap layout, and calibrated leak and symbol offsets. It also depends on nghttp2 and OpenSSL/TLS 1.3 allocation behavior, a pinned CA bundle and input-dependent allocation geometry, and the timing of two parallel transfers. The demonstrated exploit has an approximately 23-byte command constraint.
2) Improper Certificate Validation (CVE-ID: CVE-2026-8286)
CWE-ID: CWE-295 - Improper Certificate Validation
CVSSv4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass TLS certificate validation.
The vulnerability exists due to improper certificate validation in connection reuse logic for STARTTLS-enabled protocol handling when reusing an existing live connection for a new transfer. A remote attacker can cause a transfer to reuse a connection with mismatched TLS settings to bypass TLS certificate validation.
This affects transfers using IMAP, POP3, SMTP, FTP, or LDAP schemes that begin in cleartext and are upgraded to TLS with STARTTLS.
3) Insertion of Sensitive Information Into Sent Data (CVE-ID: CVE-2026-8924)
CWE-ID: CWE-201 - Insertion of Sensitive Information Into Sent Data
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper cookie domain validation in cookie parsing logic when processing a cookie with a trailing-dot domain for a trailing-dot hostname. A remote attacker can send a specially crafted HTTP response that sets a super cookie to disclose sensitive information.
This issue is exploitable through both libcurl and the curl command line tool, and it bypasses the Public Suffix List check.
4) Authentication Bypass by Capture-replay (CVE-ID: CVE-2026-8927)
CWE-ID: CWE-294 - Authentication Bypass by Capture-replay
CVSSv4: 2.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to impersonate the client to another proxy.
The vulnerability exists due to authentication bypass by capture-replay in libcurl proxy authentication state handling when reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration. A remote user can receive a leaked Proxy-Authorization header on a subsequent request to impersonate the client to another proxy.
The issue affects libcurl and does not affect the curl command line tool.
Remediation
Install update from vendor's website.