# CVE-2026-50722 — libreswan

> As of 2026-07-02, CVE-2026-50722 is a HIGH-severity vulnerability in libreswan, CVSS v3.1 7.5. No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-50722 as of 2026-07-02; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-07-02

## What is CVE-2026-50722?

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.

The record classifies CVE-2026-50722 under weakness classes [CWE-347](https://intel.threadlinqs.com/cwe/CWE-347), [CWE-617](https://intel.threadlinqs.com/cwe/CWE-617). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 95 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-02

## Is CVE-2026-50722 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **The Libreswan Project**: libreswan

## How to fix CVE-2026-50722

No vendor patch reference has been recorded for CVE-2026-50722 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-50722

No threat campaign in the Threadlinqs corpus currently references CVE-2026-50722, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, GitHub Security Advisories. Last verified by Threadlinqs on 2026-07-04. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [libreswan.org — vendor advisory](https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt)
- [libreswan.org — patch](https://libreswan.org/security/CVE-2026-50722/)

**Technical analysis**

- [rfc-editor.org — technical description](https://www.rfc-editor.org/rfc/rfc8017)

**Other references**

- [libreswan.org — related](https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-50722
Full detection coverage and IOCs for threats exploiting CVE-2026-50722 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp