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01 Record

CVE-2026-18798

QUIC Server May Trigger Double Free When Processing INITIAL Packet

HighPUBLISHEDCNA: openssl
CNA base score7.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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02 Description

QUIC Server May Trigger Double Free When Processing INITIAL Packet

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
1.69% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 77.0% of scored records. A rank, not a probability.
NVD base score
7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD analysis status
Analyzed. NVD last modified this record on 2026-09-23.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-08-25 12:59Z2 MO AGO
Last updated
2026-08-25 14:15Z2 MO AGO
Reserved
2026-08-04
Assigning CNA
openssl
Record state
PUBLISHED
Severity
High (CVSS 7.5)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
Data version
5.2
Document digest
b448a822ec9948bee70b359f6d424faee95d32377b9c35bdd86cd2f95aea89d4

05 Affected products

VendorProductVersionsPlatforms
OpenSSLOpenSSL4.0.0 to < 4.0.2, 3.6.0 to < 3.6.4, 3.5.0 to < 3.5.8—

06 References

07 Fixed in

AlmaLinux 9

  • openssl
    Fixed in 1:3.5.8-1.el9_8
  • openssl-devel
    Fixed in 1:3.5.8-1.el9_8
  • openssl-libs
    Fixed in 1:3.5.8-1.el9_8
  • openssl-perl
    Fixed in 1:3.5.8-1.el9_8

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 10

  • openssl
    Fixed in 1:3.5.8-1.el10_2.alma.1
  • openssl-devel
    Fixed in 1:3.5.8-1.el10_2.alma.1
  • openssl-libs
    Fixed in 1:3.5.8-1.el10_2.alma.1
  • openssl-perl
    Fixed in 1:3.5.8-1.el10_2.alma.1

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 9

  • openssl
    Fixed in 1:3.5.8-1.el9_8
  • openssl-devel
    Fixed in 1:3.5.8-1.el9_8
  • openssl-libs
    Fixed in 1:3.5.8-1.el9_8
  • openssl-perl
    Fixed in 1:3.5.8-1.el9_8

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 10

  • openssl
    Fixed in 1:3.5.8-1.el10_2.alma.1
  • openssl-devel
    Fixed in 1:3.5.8-1.el10_2.alma.1
  • openssl-libs
    Fixed in 1:3.5.8-1.el10_2.alma.1
  • openssl-perl
    Fixed in 1:3.5.8-1.el10_2.alma.1

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • openssl
    Fixed in 3.5.7-1~deb13u2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • openssl
    Fixed in 3.6.4-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.04 LTS

  • edk2
    No fix yet
  • edk2-hwe
    No fix yet
  • openssl
    Fixed in 3.5.5-1ubuntu3.4

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.10

  • edk2
    No fix yet
  • edk2-hwe
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 16.04 LTS

  • nodejs
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 18.04 LTS

  • nodejs
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.