high 8.1

CVE-2026-50722 json

IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload

published 2026-07-02 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-41440

cvss: 8.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 distros 5 links 1

The Libreswan Project libreswan 5.3.1

red hat almalinux rocky linux alpine azure linux

libreswan RHEL 9 5.3.2-1.el9fdp
libreswan RHEL 10.2 5.3.2-1.el10_2
libreswan-minimal RHEL 10.2 5.3.2-1.el10_2
libreswan RHEL 8 4.12-2.el8_10.6
libreswan RHEL 9 4.15-10.el9_8
libreswan RHEL 8.4 EUS_LONG_LIFE, RHEL 8.4 AUS 4.3-6.el8_4.2
libreswan RHEL 8.6 EUS_LONG_LIFE, RHEL 8.6 AUS 4.5-1.el8_6.6
libreswan RHEL 8.8 TUS, RHEL 8.8 E4S 4.9-3.el8_8.3

red hat advisories RHSA-2026:84887 RHSA-2026:82154 RHSA-2026:72287 RHSA-2026:61779 RHSA-2026:61258 RHSA-2026:57741

libreswan AlmaLinux 8 4.12-2.el8_10.6
libreswan AlmaLinux 9 4.15-10.el9_8
libreswan AlmaLinux 10 5.3.2-1.el10_2
libreswan-minimal AlmaLinux 10 5.3.2-1.el10_2

almalinux advisories ALSA-2026:46396 ALSA-2026:46397 ALSA-2026:46398

libreswan Rocky Linux 10 5.3.2-1.el10_2
libreswan Rocky Linux 8 4.12-2.el8_10.6
libreswan Rocky Linux 9 4.15-10.el9_8

rocky linux advisories RLSA-2026:46398 RLSA-2026:46396 RLSA-2026:46397

libreswan Alpine 3.23 5.3.3-r0
libreswan Alpine 3.24 5.3.2-r0

alpine advisories ALPINE-CVE-2026-50722

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

libreswan Azure Linux 3.0 4.15-2

azure linux advisories AZL-91776

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

libreswan.org/security/CVE-2026-50722/ advisory

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-50722 updated 2026-11-05 cvss 7.5

librenswan: IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload

Red Hat Enterprise Linux 6 libreswan
affected: workaround, no fix planned “Out of support scope”
Red Hat Enterprise Linux 7 libreswan Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
affected: workaround, no fix available
Red Hat Fast Datapath for Red Hat Enterprise Linux 9 libreswan 5.3.2-1.el9fdp
fixed: vendor fix RHSA-2026:46986
Red Hat Enterprise Linux AppStream (v. 8) libreswan 4.12-2.el8_10.6
fixed: vendor fix RHSA-2026:46396
Red Hat Enterprise Linux AppStream (v. 9) libreswan 4.15-10.el9_8
fixed: vendor fix RHSA-2026:46397
Red Hat Enterprise Linux AppStream (v. 10) libreswan 5.3.2-1.el10_2, libreswan-minimal 5.3.2-1.el10_2
fixed: vendor fix RHSA-2026:46398
Red Hat Enterprise Linux AppStream AUS (v.8.4) libreswan 4.3-6.el8_4.2
fixed: vendor fix RHSA-2026:84887
Red Hat Enterprise Linux AppStream AUS (v.8.6) libreswan 4.5-1.el8_6.6
fixed: vendor fix RHSA-2026:82154

show 13 more

Red Hat Enterprise Linux AppStream E4S (v.8.8) libreswan 4.9-3.el8_8.3
fixed: vendor fix RHSA-2026:72287
Red Hat Enterprise Linux AppStream E4S (v.9.2) libreswan 4.9-5.el9_2.5
fixed: vendor fix RHSA-2026:61779
Red Hat Enterprise Linux AppStream E4S (v.9.4) libreswan 4.12-3.el9_4.2
fixed: vendor fix RHSA-2026:61258
Red Hat Enterprise Linux AppStream EUS (v. 10.0) libreswan 5.2-1.el10_0.5
fixed: vendor fix RHSA-2026:55449
Red Hat Enterprise Linux AppStream EUS (v.9.6) libreswan 4.15-8.el9_6.1
fixed: vendor fix RHSA-2026:57741
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) libreswan 4.3-6.el8_4.2
fixed: vendor fix RHSA-2026:84887
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) libreswan 4.5-1.el8_6.6
fixed: vendor fix RHSA-2026:82154
Red Hat Enterprise Linux AppStream TUS (v.8.8) libreswan 4.9-3.el8_8.3
fixed: vendor fix RHSA-2026:72287
Red Hat OpenShift Container Platform 4.19 rhcos 4.19.9.6.202609021231
fixed: vendor fix RHSA-2026:63044
Red Hat OpenShift Container Platform 4.20 rhcos 4.20.9.6.202609021029
fixed: vendor fix RHSA-2026:63100
Red Hat OpenShift Container Platform 4.21 rhcos 4.21.9.6.202609021100
fixed: vendor fix RHSA-2026:63041
Red Hat Enterprise Linux AppStream AUS (v.8.4) libreswan-debuginfo 4.3-6.el8_4.2, libreswan-debugsource 4.3-6.el8_4.2 Red Hat Enterprise Linux AppStream AUS (v.8.6) libreswan-debuginfo 4.5-1.el8_6.6, libreswan-debugsource 4.5-1.el8_6.6 Red Hat Enterprise Linux AppStream E4S (v.8.8) libreswan-debuginfo 4.9-3.el8_8.3, libreswan-debugsource 4.9-3.el8_8.3 Red Hat Enterprise Linux AppStream E4S (v.9.2) libreswan-debuginfo 4.9-5.el9_2.5, libreswan-debugsource 4.9-5.el9_2.5 Red Hat Enterprise Linux AppStream E4S (v.9.4) libreswan-debuginfo 4.12-3.el9_4.2, libreswan-debugsource 4.12-3.el9_4.2 Red Hat Enterprise Linux AppStream EUS (v. 10.0) libreswan-debuginfo 5.2-1.el10_0.5, libreswan-debugsource 5.2-1.el10_0.5

+4 more productsfewer

Red Hat Enterprise Linux AppStream EUS (v.9.6) libreswan-debuginfo 4.15-8.el9_6.1, libreswan-debugsource 4.15-8.el9_6.1 Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) libreswan-debuginfo 4.3-6.el8_4.2, libreswan-debugsource 4.3-6.el8_4.2 Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) libreswan-debuginfo 4.5-1.el8_6.6, libreswan-debugsource 4.5-1.el8_6.6 Red Hat Enterprise Linux AppStream TUS (v.8.8) libreswan-debuginfo 4.9-3.el8_8.3, libreswan-debugsource 4.9-3.el8_8.3

not affected: vulnerable code not present
Red Hat OpenShift Container Platform 4 libreswan
not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 4 mo ago (2026-07-06)

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA	3.1	8.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	5.9	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

The Libreswan Project libreswan

Classification

Weakness

CWE-347 Improper Verification of Cryptographic Signature
CWE-617 Reachable Assertion

References

libreswan.org /security/CVE-2026-50722/
patch, vendor-advisory
libreswan.org /security/CVE-2026-50722/CVE-2026-50722.txt
vendor-advisory
libreswan.org /security/CVE-2026-50721/CVE-2026-50721.txt
related, vendor-advisory, mailing-list
rfc-editor.org /rfc/rfc8017
technical-description

Sources

CVE List CVE-2026-50722
NVD CVE-2026-50722

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary