CVE-2026-50722
IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload
Description
Libreswan, via the function RSA_authenticate_hash_signature_pkcs1_1_5_rsa(), did not correctly verify the DER encoding of the ASN.1 digest when the IKEv2 AUTH payload was encoded using RSASSA-PKCS1-v1_5 (RFC 8017). A remote attacker can use a variation on the Bleichenbacher attack to forge the AUTH payload when small public exponents are used (e.g., e=3), leading to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the AUTH payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of the remote IKE peer are not affected.
INFO
Published Date :
July 2, 2026, 10:16 p.m.
Last Modified :
July 9, 2026, 3:47 p.m.
Remotely Exploit :
Yes !
Source :
d42dc95b-23f1-4e06-9076-20753a0fb0df
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | d42dc95b-23f1-4e06-9076-20753a0fb0df | ||||
| CVSS 3.1 | HIGH | d42dc95b-23f1-4e06-9076-20753a0fb0df | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Libreswan to the latest version.
- Apply relevant security patches promptly.
- Verify cryptographic configurations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-50722.
| URL | Resource |
|---|---|
| https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt | Vendor Advisory Mailing List |
| https://libreswan.org/security/CVE-2026-50722/ | Vendor Advisory |
| https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt | Vendor Advisory |
| https://www.rfc-editor.org/rfc/rfc8017 | Technical Description |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-50722 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-50722
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-50722 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-50722 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 09, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:libreswan:libreswan:*:*:*:*:*:*:*:* versions up to (excluding) 5.3.1 Added Reference Type Libreswan Project: https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt Types: Mailing List, Vendor Advisory Added Reference Type Libreswan Project: https://libreswan.org/security/CVE-2026-50722/ Types: Vendor Advisory Added Reference Type Libreswan Project: https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt Types: Vendor Advisory Added Reference Type Libreswan Project: https://www.rfc-editor.org/rfc/rfc8017 Types: Technical Description -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 07, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-50722', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-06T18:12:19.317302Z'} -
New CVE Received by d42dc95b-23f1-4e06-9076-20753a0fb0df
Jul. 02, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/libreswan/libreswan', 'vendor': 'The Libreswan Project', 'product': 'libreswan', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '5.3'}, {'status': 'unaffected', 'version': '5.3.1', 'versionType': 'semver'}], 'packageName': 'libreswan', 'collectionURL': 'https://github.com/libreswan/libreswan', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'RSA_authenticate_hash_signature_pkcs1_1_5_rsa'}]}] Added Description Libreswan, via the function RSA_authenticate_hash_signature_pkcs1_1_5_rsa(), did not correctly verify the DER encoding of the ASN.1 digest when the IKEv2 AUTH payload was encoded using RSASSA-PKCS1-v1_5 (RFC 8017). A remote attacker can use a variation on the Bleichenbacher attack to forge the AUTH payload when small public exponents are used (e.g., e=3), leading to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the AUTH payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of the remote IKE peer are not affected. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-347 Added CWE CWE-617 Added Reference https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt Added Reference https://libreswan.org/security/CVE-2026-50722/ Added Reference https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt Added Reference https://www.rfc-editor.org/rfc/rfc8017