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VulnerabilityPublished Updated

CVE-2026-18798: Issue summary · QUIC server may double free QRX (QUIC record layer RX) object when channel creation

Affects nodejsSource GCVE Database

0

Not known to be exploited · CVSS 7.5 High : upgrade to 3.5.5-1ubuntu3.4 soon.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.6% chance of exploitation in 30 days – higher than 77% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.5.5-1ubuntu3.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade the Ubuntu openssl package to 3.5.5-1ubuntu3.4.

Affected software

ProductAffectedFixed in
Ubuntu 26.10edk2pkg:deb/ubuntu/edk2?arch=source&distro=stonkingOther threatsAffected
  • 2025.11-3ubuntu7 – 2026.05-2ubuntu3
5 affected builds
Fixed in–
Ubuntu 26.10edk2-hwepkg:deb/ubuntu/edk2-hwe?arch=source&distro=stonkingOther threatsAffected
  • 2025.11-3ubuntu8 – 2026.05-2ubuntu3
5 affected builds
Fixed in–
Ubuntu 26.04 LTSedk2pkg:deb/ubuntu/edk2?arch=source&distro=resoluteOther threatsAffected
  • 2025.02-8ubuntu3 – 2025.11-3ubuntu7.3
5 affected builds
Fixed in–
Ubuntu 26.04 LTSedk2-hwepkg:deb/ubuntu/edk2-hwe?arch=source&distro=resoluteOther threatsAffected
  • =2025.11-3ubuntu6
  • =2025.11-3ubuntu8
  • =2025.11-3ubuntu8.2
Fixed in–
Ubuntu 26.04 LTSopensslpkg:deb/ubuntu/openssl?arch=source&distro=resoluteOther threatsAffected
  • <3.5.5-1ubuntu3.4
Fixed in
  • 3.5.5-1ubuntu3.4
Ubuntu Pro 18.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 6.11.4~dfsg-1ubuntu1 – 8.10.0~dfsg-2ubuntu0.4+esm6
15 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

Issue summary: QUIC server may double free QRX (QUIC record layer RX) object when channel creation fails for initial packet. Impact summary: Double free leads to heap corruption, which typically results in termination of QUIC server process, leading to Denial of Service. There is so far no evidence that this double free is exploitable for remote code execution, thus it is considered highly improbable. CWE: CWE-415: Double Free Description: In order to validate initial packet, OpenSSL QUIC stack default packet handler (port_default_packet_handler()) creates a so-called QRX object. If the initial packet validates successfully with QRX object, the default packet handler proceeds to channel (connection object) creation. The QRX object used for packet validation is passed to port_bind_channel(), so it becomes part of the newly created connection. If port_bind_channel() fails, then it also frees the QRX object. Once port_bind_channel() returns, the port_default_packet_handler() detects the failure and proceeds to the error branch, where the same QRX object is freed for the second time. The failure in port_bind_channel() function can be induced with a relatively low effort by a malformed (non RFC 9000 compliant) INITIAL packet. If the packet carries DCID (destination connection ID) which is shorter than 8 bytes, then port_bind_channel() jumps to the error path after ossl_quic_lcidm_enrol_odcid() detects that the DCID has invalid length. FIPS impact: no The FIPS module is not affected, as the QUIC implementation is outside of the OpenSSL FIPS module boundary.

References

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