CVE-2026-63384

HIGHPre-NVD 8.78.7
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (42nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-63507 (ENISA EUVD)Source: ENISA EUVD

8.7EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 8.7Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an incorrect integer conversion in event_tagging.c when evtag_unmarshal_header uses evtag_decode_int to decode an attacker-controlled uint32 payload length and returns it as a signed int. Values above INT_MAX become negative or truncated, and evtag_unmarshal_string can use the converted value in allocation sizing, producing a wrapped large allocation request and denial of service. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

CVSS
8.7
EG Score
8.7HIGHmedium confidence
EG Risk
70
EG Risk 70/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity87% × 45%
Impact severity (EG Severity): CVSS 8.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
42nd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (8.7): severity, escalated by confirmed exploitation. This CVE's 8.7 is its impact severity (EG Severity), not escalated.

EG Severity
8.7 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-10). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 20, 2026

Last Modified

October 26, 2026

Advisory Details (5)

Auto-updated Aug 20, 2026
Patch available. Sources: github, github_commit, github_release.
GitHub release Patch Available

Libevent 2.2.2-alpha

Patch available: libevent/libevent release-2.2.2-alpha

https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
GitHub release Patch Available

Libevent 2.1.13-stable

Patch available: libevent/libevent release-2.1.13-stable

https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
GitHub commit Patch Available

commit 5e3c6ebe342b (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit 5e3c6ebe342b)

https://github.com/libevent/libevent/commit/5e3c6ebe342b34c5a9bcf48e9a32ad6708b9c416
GitHub commit Patch Available

commit 109c16499282 (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 109c16499282)

https://github.com/libevent/libevent/commit/109c16499282959d70f56ec3baf4c8b1e6646bda
GitHub advisoryMentions a patch (unverified)

`evtag_unmarshal_header()` decodes a wire `uint32` length into a signed `int` return value. · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8

Patch Availability(13)

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

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
libevent2.1.12-stable-8
  • every version up to 2.1.12-stable-8+deb12u1: fixed in 2.1.12-stable-8+deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libevent2.1.12-stable-10
  • every version up to 2.1.13-stable-1~deb13u1: fixed in 2.1.13-stable-1~deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libevent2.1.12-stable-10, 2.1.13-stable-1~deb13u1
  • every version up to 2.1.13-stable-1: fixed in 2.1.13-stable-1
—

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 8× in last 7d / 34× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 216 rows on record for this CVE, as 98 entries (2 repeats merged).

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 2 repeat rows among the latest 100 are merged into the row they repeat. The 116 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  2. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  3. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  4. 2026-11-11 07:33 UTCEchelonGraph re-scored
  5. 2026-11-11 07:33 UTCVendor advisory
  6. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  7. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  8. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  9. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  10. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  11. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  13. 2026-11-04 02:19 UTCEchelonGraph re-scored
  14. 2026-11-04 02:19 UTCVendor advisory
  15. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  16. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  17. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  18. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  19. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  20. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  21. 2026-10-27 21:05 UTCEchelonGraph re-scored
  22. 2026-10-27 21:05 UTCVendor advisory
  23. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  24. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  25. 2026-10-26 10:26 UTCEchelonGraph re-scored
Show 73 more
  1. 2026-10-26 10:26 UTCVendor advisory
  2. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  3. 2026-10-25 14:13 UTCEchelonGraph re-scored
  4. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  5. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  6. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  8. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  9. 2026-10-20 09:17 UTCEchelonGraph re-scored
  10. 2026-10-20 09:17 UTCVendor advisory
  11. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  12. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  13. 2026-10-18 03:23 UTCEchelonGraph re-scored
  14. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  15. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  16. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  17. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  18. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  20. 2026-10-12 15:40 UTCEchelonGraph re-scored
  21. 2026-10-12 15:40 UTCVendor advisory
  22. 2026-10-11 19:33 UTCEchelonGraph re-scored
  23. 2026-10-11 16:48 UTCEchelonGraph re-scored
  24. 2026-10-11 14:10 UTCEchelonGraph re-scored
  25. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  26. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  27. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  28. 2026-10-09 08:27 UTCEchelonGraph re-scored
  29. 2026-10-09 08:27 UTCVendor advisory
  30. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  31. 2026-10-08 05:22 UTCEchelonGraph re-scored
  32. 2026-10-08 05:22 UTCVendor advisory
  33. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  34. 2026-10-07 03:49 UTCVendor advisory
  35. 2026-10-06 16:53 UTCEchelonGraph re-scored
  36. 2026-10-06 16:53 UTCVendor advisory
  37. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  38. 2026-10-06 03:25 UTCVendor advisory
  39. 2026-10-06 03:24 UTCEchelonGraph re-scored
  40. 2026-10-06 03:24 UTCVendor advisory
  41. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  42. 2026-10-05 13:52 UTCVendor advisory
  43. 2026-10-05 02:33 UTCEchelonGraph re-scored
  44. 2026-10-05 02:33 UTCVendor advisory
  45. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  46. 2026-10-04 15:41 UTCVendor advisory
  47. 2026-10-04 04:22 UTCVendor advisory
  48. 2026-10-03 17:29 UTCEchelonGraph re-scored
  49. 2026-10-03 17:29 UTCVendor advisory
  50. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  51. 2026-10-03 06:38 UTCVendor advisory
  52. 2026-10-02 19:18 UTCEchelonGraph re-scored
  53. 2026-10-02 19:18 UTCVendor advisory
  54. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  55. 2026-10-02 08:20 UTCVendor advisory
  56. 2026-10-01 21:29 UTCEchelonGraph re-scored
  57. 2026-10-01 21:29 UTCVendor advisory
  58. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  59. 2026-10-01 07:22 UTCVendor advisory
  60. 2026-09-30 20:31 UTCEchelonGraph re-scored
  61. 2026-09-30 20:31 UTCVendor advisory
  62. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  63. 2026-09-30 08:13 UTCEchelonGraph re-scored
  64. 2026-09-30 08:13 UTCVendor advisory
  65. 2026-09-29 00:32 UTCEchelonGraph re-scored
  66. 2026-09-29 00:32 UTCVendor advisory
  67. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  68. 2026-09-28 13:40 UTCVendor advisory
  69. 2026-09-28 02:48 UTCVendor advisory
  70. 2026-09-27 15:57 UTCEchelonGraph re-scored
  71. 2026-09-27 15:57 UTCVendor advisory
  72. 2026-09-27 03:00 UTCEchelonGraph re-scored
  73. 2026-09-27 03:00 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-63384?
CVE-2026-63384 is a high-severity vulnerability; its CVE record was published on August 20, 2026. Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an incorrect integer conversion in event_tagging.c when evtag_unmarshal_header uses evtag_decode_int to decode an attacker-controlled uint32 payload length and returns it as a signed int. Values above INT_MAX…
When was the CVE record for CVE-2026-63384 published?
The CVE record for CVE-2026-63384 was published on August 20, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-63384 actively exploited?
CVE-2026-63384 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (42nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63384?
CVE-2026-63384 has a CVSS base score of 8.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63384?
A fix for CVE-2026-63384 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63384 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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