CVE-2026-78133: libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling

Distribution release	Source package	Vendor state	Fixed version	Evidence
Debian trixietrixie · source	`strongswan`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.0.1-6+deb13u7`	Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · source	`strongswan`	Not affectedDebian marks this release not affected (fixed-version marker 0).	`Not published in this feed`	Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · source	`strongswan`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.1.0-1`	Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · source	`strongswan`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.1.0-1`	Debian Security Tracker ↗Source updated 5 Oct 2026

Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available

What, why and how

libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling.

What

libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling.

Why

The program can continue using memory after it has been released, producing unsafe and attacker-influenceable behaviour.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling.

Why

The program can continue using memory after it has been released, producing unsafe and attacker-influenceable behaviour.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: a network path → Use After Free → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Network
Privileges required: Low: a basic authenticated account is required
User interaction: None
Attack complexity: High: exploitation depends on specific conditions
Security boundary: Unchanged: impact remains within the vulnerable component's security authority
Weakness ? CWE means Common Weakness Enumeration: a standard category for the underlying weakness.: CWE-416 ↗
CWE-416: Use After Free. The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land: No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.

NetworkCWE-416

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-75907Official EUVD mapping

libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling.

Official EUVD record ↗

BSI · German · WID-SEC-2026-3230strongSwan: Mehrere Schwachstellen

Ein entfernter, authentisierter Angreifer kann mehrere Schwachstellen in strongSwan ausnutzen, um einen Denial of Service zu verursachen, Sicherheitsmaßnahmen zu umgehen, Informationen offenzulegen und Code auszuführen.

Official advisory ↗

Cyber Security Agency of Singapore · English · CSA-SB-20260916Security Bulletin 16 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 16 Sep 2026, published on 16 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗

CERT-FR · French · CERTFR-2026-AVI-1129Multiples vulnérabilités dans strongSwan

De multiples vulnérabilités ont été découvertes dans strongSwan. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et un contournement de la politique de sécurité.

Official advisory ↗

CSIRT Italia · Italian · sanate-vulnerabilita-in-strongswanSanate vulnerabilità in strongSwan

Sanate molteplici vulnerabilità di sicurezza, di cui 4 con gravità “alta” in strongSwan, noto software open-source per la realizzazione di connessioni VPN. Tali vulnerabilità, qualora sfruttate, potrebbero consentire ad un utente remoto malintenzionato di compromettere la disponibilità del servizio e, in taluni casi, eseguire codice arbitrario sui sistemi interessati.

Official advisory ↗

JVN iPedia · Japanese · JVNDB-2026-033622strongSwanにおける解放済みメモリの使用に関する脆弱性

strongSwan 6.0.0 から 6.0.7 までの libcharon において、IKEv2 の再鍵処理時の衝突処理で use-after-free の脆弱性が存在します。

Official advisory ↗

Patch and workaround

Operational remediation based on structured source evidence.

Status ? Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.: Patch available
Affected: strongSwan: 6.0.0 < 6.1.0
Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action: Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround: A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.

Official vendor articles1 stored document

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

Release strongSwan 6.1.0 · strongswan/strongswan · GitHub →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026strongswan / strongswan Public Notifications You must be signed in to change notification settings Fork 938 Star 3k Code Issues 107 Pull requests 66 Discussions Actions Security and quality 0 Insights Additional navigation options Code Issues Pull requests Discussions Actions Security and quality Insig

Evidence and provenance

Published 11 Sept 2026 · Last source change 11 Sept 2026, 16:54 UTC · CWE-416 · Use After Free

CVE recordCVE.org · 5.2

CVSS sourceCNA

EPSS source

The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.

FIRST · tracked since 2026-09-11

European sourceENISA EUVD · EUVD-2026-75907

Product sourceCNA

Remediation sourceCVE/CNA references

CWE sourceCNA

NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

11 Sep 2026, 16:54 UTC
Vendor guidanceAuthoritative vendor guidance changed: added mitigation: strongswan.org/strongswan-vulnerability-(cve-2026-78133).html; added patch: github.com/6.1.0; 1 further additions.
Before
no authoritative guidance recorded
After
mitigation: strongswan.org/strongswan-vulnerability-(cve-2026-78133).html · patch: github.com/6.1.0 · remediation: github.com/6.1.0
cve@mitre.org ↗
11 Sep 2026, 16:54 UTC
Affected versionsThe structured affected or fixed version information changed.
Before
strongSwan: 6.0.0 < 6.1.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
After
strongSwan: 6.0.0 < 6.1.0 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
CNA ↗
11 Sep 2026, 16:54 UTC
Remediation statusRemediation status changed from Awaiting fix to Patch available.
Before
Awaiting fix
After
Patch available
cve@mitre.org ↗
11 Sep 2026, 16:54 UTC
Affected versionsThe structured affected or fixed version information changed.
Before
6.0.0 < 6.1.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
After
strongSwan: 6.0.0 < 6.1.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
CNA ↗
11 Sep 2026, 12:52 UTC
ENISA EUVD mappingEUVD-2026-75907 was added to the official ENISA EUVD mapping for this CVE.
Before
not recorded
After
{"euvdId":"EUVD-2026-75907"}
ENISA EUVD ↗
11 Sep 2026, 01:52 UTC
Catalogue recordCVE added to the BlackTree catalogue.
CNA ↗

2026-09-11CVE published

2026-09-11Fixed release or patch reference recorded

ENISA EUVD · EUVD-2026-75907↗CVE authority or vendor reference↗Mitigation reference↗Official CVE record (CNA and ADP data)↗NVD record↗

Technical terms and abbreviations used in this report

CVE: Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS: Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS: Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE: Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA: CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP: Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD: National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT: A computer security incident response team that publishes warnings or coordinates incident response.
PoC: Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF: Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL: Living off the land: abuse of legitimate tools or system functions during an attack.

libcharon in strongSwan 6.0.0 through 6.0.7 has a use-after-free in IKEv2 rekeying collision handling

Published severity in operational context

Evidence used

Compensating controls

Verification

Release-specific package status

National CERT insights
?
CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

ENISA European Vulnerability Database

EUVD-2026-75907

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

What changed after publication