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Fencer Intel
low 3.7

CVE-2026-77205 json

Denial of Service via sending bogus X.509 certificates

published 29d ago modified 26d ago also EUVD-2026-100747

cvss
3.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

Libreswan in FIPS mode has a vulnerability where badly formed received certificates are rejected, but not deleted from the NSS cache. As a result, any real certificates with the same serial number are rejected as well. This can be abused to lock out legitimate peers from connecting. The add_decoded_cert() function missed a call to CERT_DestroyCertificate() due to an incorrect fix for CVE-2026-14957. Sending bogus certificates with new serial numbers could prevent the real certificates with those serial numbers from connecting until the service has restarted.

Patch / fix

  • The Libreswan Project libreswan 5.3.3
  • libreswan AlmaLinux 10 5.3.3-1.el10_2
  • libreswan-minimal AlmaLinux 10 5.3.3-1.el10_2

almalinux advisories ALSA-2026:89923

  • libreswan Rocky Linux 10 5.3.3-1.el10_2

rocky linux advisories RLSA-2026:89923

  • libreswan Alpine 3.24, Alpine 3.23 5.3.3-r0

alpine advisories ALPINE-CVE-2026-77205

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

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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-2026-77205 updated cvss 3.7

libreswan: Denial of Service via sending bogus X.509 certificates

  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Disabling FIPS mode will prevent this attack vector. However, disabling FIPS mode may violate security or compliance requirements and should not be used as a workaround without authorization.”
  • Red Hat Fast Datapath for Red Hat Enterprise Linux 9 libreswan 5.3.3-3.el9fdp
    fixed: vendor fix “Disabling FIPS mode will prevent this attack vector. However, disabling FIPS mode may violate security or compliance requirements and should not be used as a workaround without authorization.” RHSA-2026:98046
  • Red Hat Enterprise Linux AppStream (v. 10) libreswan 5.3.3-1.el10_2, libreswan-minimal 5.3.3-1.el10_2
    fixed: vendor fix “Disabling FIPS mode will prevent this attack vector. However, disabling FIPS mode may violate security or compliance requirements and should not be used as a workaround without authorization.” RHSA-2026:89923
  • Red Hat Enterprise Linux 6 libreswan Red Hat Enterprise Linux 7 libreswan Red Hat Enterprise Linux 8 libreswan Red Hat Enterprise Linux 9 libreswan Red Hat OpenShift Container Platform 4 libreswan
    not affected: vulnerable code 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
no
Technical impact
partial
Assessed
26d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected products

  • The Libreswan Project libreswan

Classification

Weakness
  • CWE-772 Missing Release of Resource after Effective Lifetime

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.