CVE-2026-5244

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.8% (55th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 7.3 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-04-02) is not newer than that change (2026-10-26), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2026-18170 (ENISA EUVD) · GHSA-7vfw-f3r2-9m2j (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
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).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A vulnerability has been found in Cesanta Mongoose up to 7.20. This affects the function mg_tls_recv_cert of the file mongoose.c of the component TLS 1.3 Handler. Such manipulation of the argument pubkey leads to heap-based buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 7.21 mitigates this issue. The name of the patch is 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. It is advisable to upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
59
EG Risk 59/100

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)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.8% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
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 none (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
0.8%
EPSS %ILE
55th
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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-30). 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: 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 none (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.

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

April 2, 2026

Last Modified

October 26, 2026

Advisory Details (3)

Auto-updated Oct 26, 2026
Patch available. Sources: github_commit, github_release.
GitHub release Patch Available

Mongoose 7.21

Patch available: cesanta/mongoose 7.21

https://github.com/cesanta/mongoose/releases/tag/7.21
GitHub commit Patch Available

commit 0d882f1b43ff (cesanta/mongoose)

Patch available: cesanta/mongoose 7.21 (contains commit 0d882f1b43ff)

https://github.com/cesanta/mongoose/commit/0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1
Web page

GitHub - cesanta/mongoose: Embedded web server, with TCP/IP network stack, MQTT and Websocket · GitHub

https://github.com/cesanta/mongoose/

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
swupdate2020.11-2 ... 2026.05.1+dfsg-1~bpo13+1 (69 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
swupdate2022.12+dfsg-4 ... 2026.05.1+dfsg-1~bpo13+1 (55 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
swupdate2024.12.1+dfsg-3 ... 2026.05.1+dfsg-1~bpo13+1 (29 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
swupdate2024.12.1+dfsg-3 ... 2025.12+dfsg-9 (19 versions)
  • every version up to 2025.12+dfsg-10: fixed in 2025.12+dfsg-10
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 52× 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 it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 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). Most recent first.

Showing the most recent 100 of 243 refreshes on record for this CVE.

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. None are among the latest 100 rows. The 143 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-31 12:44 UTCEG score recompute
  2. 2026-10-31 12:44 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  3. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  4. 2026-10-30 12:50 UTCEG score recompute
  5. 2026-10-30 12:50 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  6. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.7% · 54th percentile
  7. 2026-10-29 12:50 UTCEG score recompute
  8. 2026-10-29 12:50 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  9. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.7% · 54th percentile
  10. 2026-10-28 12:55 UTCEG score recompute
  11. 2026-10-28 12:55 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  12. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  13. 2026-10-27 13:00 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  14. 2026-10-26 22:38 UTCEG score recompute▲ 2.50
  15. 2026-10-26 22:37 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  16. 2026-10-26 22:26 UTCNVD updateCVSS v3 → 9.8 · CVSS v4 → 5.5 · severity → CRITICAL
  17. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  18. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  19. 2026-10-25 14:21 UTCEG score recompute
  20. 2026-10-25 01:11 UTCEG score recompute
  21. 2026-10-25 01:10 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  22. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  23. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  24. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  25. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
Show 75 more
  1. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  2. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  3. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  4. 2026-10-18 03:32 UTCEG score recompute
  5. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  6. 2026-10-17 11:26 UTCEG score recompute
  7. 2026-10-17 11:25 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  8. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  9. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  10. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  11. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  12. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  13. 2026-10-12 15:58 UTCEG score recompute
  14. 2026-10-11 19:41 UTCEG score recompute
  15. 2026-10-11 16:56 UTCEG score recompute
  16. 2026-10-11 14:20 UTCEG score recompute
  17. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  18. 2026-10-11 02:31 UTCOSV refresh
  19. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  20. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  21. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  22. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  23. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  24. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  25. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  26. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  27. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  28. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  29. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  30. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  31. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  32. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  33. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  34. 2026-09-21 14:19 UTCOSV refresh
  35. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  36. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  37. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  38. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  39. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  40. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  41. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  42. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  43. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  44. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  45. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  46. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  47. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  48. 2026-09-02 11:34 UTCOSV refresh
  49. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  50. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  51. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  52. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  53. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  54. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  55. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  56. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  57. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  58. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  59. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  60. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  61. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  62. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  63. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  64. 2026-08-16 09:27 UTCEG score recompute
  65. 2026-08-16 09:27 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  66. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  67. 2026-08-14 19:01 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  68. 2026-08-14 05:52 UTCEG score recompute
  69. 2026-08-14 05:52 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  70. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  71. 2026-08-13 10:00 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  72. 2026-08-12 20:10 UTCEG score recompute
  73. 2026-08-12 20:10 UTCGHSA enrichmentGHSA-7vfw-f3r2-9m2j · GitHub CVSS 7.3
  74. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  75. 2026-08-11 20:30 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-5244?
CVE-2026-5244 is a critical-severity vulnerability; its CVE record was published on April 2, 2026. A vulnerability has been found in Cesanta Mongoose up to 7.20. This affects the function mgtlsrecv_cert of the file mongoose.c of the component TLS 1.3 Handler. Such manipulation of the argument pubkey leads to heap-based buffer overflow. The attack may be launched remotely. The exploit has been…
When was the CVE record for CVE-2026-5244 published?
The CVE record for CVE-2026-5244 was published on April 2, 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-2026-5244 actively exploited?
CVE-2026-5244 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (55th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-5244?
CVE-2026-5244 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-5244?
A fix for CVE-2026-5244 is available: update to the fixed version the vendor names in its advisory.

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