CVE-2026-78129: strongSwan 4.6.2 through 6.0.7 has an infinite loop in PKCS#5 decryption.

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2026-78129 is a medium-severity flaw (CVSS 5.9) affecting strongswan. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

strongSwan 4.6.2 through 6.0.7 has an infinite loop in PKCS#5 decryption.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-835
Published	2026-09-11
Last modified	2026-09-14

Publisher (CNA): MITRE · Vendor: strongswan

Last updated 2026-09-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-11 02:18 UTCPublished CVE record published
2026-09-14 20:08 UTCUpdated Record last modified

strongswan strongswan UPGRADE

Affected: >= 4.6.2 and < 6.1.0

Fixed in: 6.1.0

Safe to downgrade to: a release before 4.6.2

1. Check installed version

apt-cache policy strongswan || rpm -q strongswan || strongswan --version

2. UPGRADE to 6.1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade strongswan

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade strongswan

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.6.2 (Debian / Ubuntu)

apt-cache madison strongswan sudo apt install strongswan=<VERSION_BEFORE_4.6.2> sudo apt-mark hold strongswan

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list strongswan sudo dnf downgrade strongswan-<VERSION_BEFORE_4.6.2> sudo dnf versionlock add strongswan

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-78129?

strongswan: upgrade to 6.1.0. Exact commands for each OS are on this page.

Is CVE-2026-78129 being exploited?

CVE-2026-78129 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-78129 affect?

CVE-2026-78129 affects strongswan. Severity is medium (CVSS 5.9). strongSwan 4.6.2 through 6.0.7 has an infinite loop in PKCS#5 decryption.

How urgent is CVE-2026-78129?

Priority 36/100. Remotely exploitable, no login, no user action

Software pages

strongSwan vulnerabilities

Related CVEs

CVE-2026-78135 MEDIUM 5.6 UPGRADE libcharon in strongSwan 5.9.7 through 6.0.7 mishandles behavioral workflow in the IKEv2 state machine
CVE-2026-78130 HIGH 7.5 UPGRADE strongSwan 4.2.0 through 6.0.7 has a NULL pointer dereference in the x509 plugin's attribute certificate parse
CVE-2026-78123 MEDIUM 5.9 UPGRADE strongSwan 5.0.2 through 6.0.7 has an Expired Pointer Dereference in PKCS#7 parsing in the openssl plugin.
CVE-2026-78124 LOW 3.7 UPGRADE strongSwan 5.0.2 through 6.0.7 allows PKCS#7 certificate enumeration in the openssl plugin that leads to a lac
CVE-2026-78126 MEDIUM 5.9 UPGRADE strongSwan 4.1.10 through 6.0.7 allows a NULL pointer dereference in the eap-aka plugin.

References

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