CVE-2026-18798

HIGHPre-NVD 7.57.5
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-25. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — Patch released this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
73%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 28, 2026

Advisory Details (4)

Auto-updated Aug 25, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
github_commit

commit 967582d5037f (openssl/openssl)

Fix landed in openssl/openssl commit 967582d5037f — awaiting tagged release

https://github.com/openssl/openssl/commit/967582d5037f01a26b6d19beae19af62a1b15c3c
github_commit

commit 70cebd74d359 (openssl/openssl)

Fix landed in openssl/openssl commit 70cebd74d359 — awaiting tagged release

https://github.com/openssl/openssl/commit/70cebd74d3592f5272945501b58a60374c4e13af
github_commit

commit a14a1deac403 (openssl/openssl)

Fix landed in openssl/openssl commit a14a1deac403 — awaiting tagged release

https://github.com/openssl/openssl/commit/a14a1deac403522fbeafabcb198503cf6caa7dc4

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuopenssl (3.0.13-0ubuntu3.15) @ noble2026-09-19ubuntu
redhatopenssl-1:3.5.8-1.el10_22026-09-14redhat
redhatopenssl-1:3.5.8-1.el9_82026-09-14redhat
redhatopenssl-main-3.5.8-0.1.hum12026-08-25redhat
redhatopenssl3-main-3.5.8-0.1.hum12026-08-25redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 5 ecosystems)
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
openssl3.5.8-r0
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
openssl3.5.8-r0
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
openssl3.5.8-r0
Debian:13(1)
PackageVulnerable rangeFixed inDependents
openssl3.5.1-1 ... 3.5.7-1~deb13u1 (13 versions)3.5.7-1~deb13u2
Debian:14(1)
PackageVulnerable rangeFixed inDependents
openssl3.5.1-1 ... 4.0.2-1 (28 versions)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 38× in last 7d / 140× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 140 total refreshes for this CVE.

  1. 2026-09-19 01:16 UTCEG score recompute
  2. 2026-09-19 01:16 UTCVendor advisory
  3. 2026-09-19 01:15 UTCGHSA enrichment
  4. 2026-09-18 19:27 UTCEPSS rescore
  5. 2026-09-18 12:40 UTCVendor advisory
  6. 2026-09-18 12:40 UTCGHSA enrichment
  7. 2026-09-18 00:05 UTCEG score recompute
  8. 2026-09-18 00:05 UTCVendor advisory
  9. 2026-09-18 00:05 UTCGHSA enrichment
  10. 2026-09-17 11:15 UTCVendor advisory
  11. 2026-09-17 11:15 UTCGHSA enrichment
  12. 2026-09-16 22:40 UTCEG score recompute
  13. 2026-09-16 22:40 UTCVendor advisory
  14. 2026-09-16 22:40 UTCGHSA enrichment
  15. 2026-09-16 14:07 UTCEPSS rescore
  16. 2026-09-16 09:40 UTCEG score recompute
  17. 2026-09-16 09:40 UTCVendor advisory
  18. 2026-09-16 09:40 UTCGHSA enrichment
  19. 2026-09-16 05:14 UTCEPSS rescore
  20. 2026-09-15 21:05 UTCVendor advisory
  21. 2026-09-15 21:05 UTCGHSA enrichment
  22. 2026-09-15 08:28 UTCEG score recompute
  23. 2026-09-15 08:28 UTCVendor advisory
  24. 2026-09-15 08:28 UTCGHSA enrichment
  25. 2026-09-14 19:52 UTCVendor advisory
Show 75 more
  1. 2026-09-14 19:52 UTCGHSA enrichment
  2. 2026-09-14 07:15 UTCVendor advisory
  3. 2026-09-14 07:15 UTCGHSA enrichment
  4. 2026-09-13 18:40 UTCEG score recompute
  5. 2026-09-13 18:40 UTCVendor advisory
  6. 2026-09-13 18:40 UTCGHSA enrichment
  7. 2026-09-13 16:46 UTCEPSS rescore
  8. 2026-09-13 06:04 UTCVendor advisory
  9. 2026-09-13 06:04 UTCGHSA enrichment
  10. 2026-09-12 17:29 UTCEG score recompute
  11. 2026-09-12 17:29 UTCVendor advisory
  12. 2026-09-12 17:29 UTCGHSA enrichment
  13. 2026-09-12 15:00 UTCEPSS rescore
  14. 2026-09-12 04:54 UTCVendor advisory
  15. 2026-09-12 04:54 UTCGHSA enrichment
  16. 2026-09-11 16:19 UTCEG score recompute
  17. 2026-09-11 16:19 UTCVendor advisory
  18. 2026-09-11 16:19 UTCGHSA enrichment
  19. 2026-09-11 14:52 UTCEPSS rescore
  20. 2026-09-11 09:36 UTCEPSS rescore
  21. 2026-09-11 03:44 UTCVendor advisory
  22. 2026-09-11 03:44 UTCGHSA enrichment
  23. 2026-09-10 15:08 UTCEG score recompute
  24. 2026-09-10 15:08 UTCVendor advisory
  25. 2026-09-10 15:08 UTCGHSA enrichment
  26. 2026-09-10 09:34 UTCEPSS rescore
  27. 2026-09-10 02:32 UTCVendor advisory
  28. 2026-09-10 02:32 UTCGHSA enrichment
  29. 2026-09-09 13:57 UTCVendor advisory
  30. 2026-09-09 13:57 UTCGHSA enrichment
  31. 2026-09-09 01:16 UTCEG score recompute
  32. 2026-09-09 01:16 UTCVendor advisory
  33. 2026-09-09 01:16 UTCGHSA enrichment
  34. 2026-09-08 22:00 UTCEPSS rescore
  35. 2026-09-07 20:42 UTCEG score recompute
  36. 2026-09-07 20:42 UTCVendor advisory
  37. 2026-09-07 20:42 UTCGHSA enrichment
  38. 2026-09-07 16:01 UTCEPSS rescore
  39. 2026-09-07 08:05 UTCVendor advisory
  40. 2026-09-07 08:05 UTCGHSA enrichment
  41. 2026-09-06 19:10 UTCEG score recompute
  42. 2026-09-06 19:10 UTCVendor advisory
  43. 2026-09-06 19:10 UTCGHSA enrichment
  44. 2026-09-06 13:47 UTCEPSS rescore
  45. 2026-09-06 06:31 UTCVendor advisory
  46. 2026-09-06 06:31 UTCGHSA enrichment
  47. 2026-09-05 17:55 UTCEG score recompute
  48. 2026-09-05 17:55 UTCVendor advisory
  49. 2026-09-05 17:55 UTCGHSA enrichment
  50. 2026-09-05 05:18 UTCVendor advisory
  51. 2026-09-05 05:18 UTCGHSA enrichment
  52. 2026-09-04 16:39 UTCEG score recompute
  53. 2026-09-04 16:39 UTCVendor advisory
  54. 2026-09-04 16:39 UTCGHSA enrichment
  55. 2026-09-04 05:06 UTCEPSS rescore
  56. 2026-09-04 04:01 UTCVendor advisory
  57. 2026-09-04 04:01 UTCGHSA enrichment
  58. 2026-09-03 15:23 UTCVendor advisory
  59. 2026-09-03 15:22 UTCGHSA enrichment
  60. 2026-09-03 02:45 UTCEG score recompute
  61. 2026-09-03 02:45 UTCVendor advisory
  62. 2026-09-03 02:45 UTCGHSA enrichment
  63. 2026-09-02 14:11 UTCEPSS rescore
  64. 2026-09-02 14:09 UTCVendor advisory
  65. 2026-09-02 14:08 UTCGHSA enrichment
  66. 2026-09-02 01:25 UTCEG score recompute
  67. 2026-09-02 01:25 UTCVendor advisory
  68. 2026-09-02 01:25 UTCGHSA enrichment
  69. 2026-09-01 13:53 UTCEPSS rescore
  70. 2026-09-01 12:40 UTCEG score recompute
  71. 2026-09-01 12:40 UTCVendor advisory
  72. 2026-09-01 12:40 UTCGHSA enrichment
  73. 2026-09-01 04:39 UTCEPSS rescore
  74. 2026-08-31 23:41 UTCVendor advisory
  75. 2026-08-31 23:41 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-18798?
CVE-2026-18798 is a high vulnerability published on August 25, 2026. 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…
When was CVE-2026-18798 disclosed?
CVE-2026-18798 was first published in the National Vulnerability Database on August 25, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-18798 actively exploited?
CVE-2026-18798 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 27.2% of all scored CVEs.
What is the CVSS score of CVE-2026-18798?
CVE-2026-18798 has a CVSS v3.1 base score of 7.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-18798?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-18798, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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