Nixpkgs security tracker

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Permalink CVE-2026-55199

8.2 HIGH

CVSS version (CVSS): 4.0
Attack Vector (AV): Network (N)
Attack Complexity (AC): Low (L)
Attack Requirement (AT): Present (P)
Privileges Required (PR): None (N)
User Interaction (UI): None (N)
Vulnerable System Impact Confidentiality (VC): None (N)
Vulnerable System Impact Integrity (VI): None (N)
Vulnerable System Impact Availability (VA): High (H)
Subsequent System Impact Confidentiality (SC): None (N)
Subsequent System Impact Integrity (SI): None (N)
Subsequent System Impact Availability (SA): None (N)
Modified Attack Vector (MAV): Network (N)
Modified Attack Complexity (MAC): Low (L)
Modified Attack Requirement (MAT): Present (P)
Modified Privileges Required (MPR): None (N)
Modified User Interaction (MUI): None (N)
Modified Vulnerable System Impact Confidentiality (MVC): None (N)
Modified Vulnerable System Impact Integrity (MVI): None (N)
Modified Vulnerable System Impact Availability (MVA): High (H)
Modified Subsequent System Impact Confidentiality (MSC): Negligible (N)
Modified Subsequent System Impact Integrity (MSI): Negligible (N)
Modified Subsequent System Impact Availability (MSA): Negligible (N)
Safety (S): Not Defined (X)
Automatable (AU): Not Defined (X)
Recovery (R): Not Defined (X)
Value Density (V): Not Defined (X)
Vulnerability Response Effort (RE): Not Defined (X)
Provider Urgency (U): Not Defined (X)
Confidentiality Req. (CR): Not Defined (X)
Integrity Req. (IR): Not Defined (X)
Availability Req. (AR): Not Defined (X)
Exploit Maturity (E): Not Defined (X)

created 3 weeks, 6 days ago Activity log

Created suggestion 3 weeks, 6 days ago

libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handler

libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.