CVE-2026-73257

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7% (52nd 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-2026-63492 (ENISA EUVD)Source: ENISA EUVD

9.1EG
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: 0.7%CVSS: 9.1Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

Mongoose is an embedded web server and network library. Priro to version 7.22, a remote unauthenticated attacker can send an HTTP request containing both Content-Length and Transfer-Encoding: chunked. The cl_count and te_count checks in the mg_http_parse() and http_cb() paths in src/http.c accept both headers and prioritize chunked encoding, while a Content-Length-preferring reverse proxy can use a different request boundary. This CL.TE desynchronization can inject requests that access or modify resources in another user context. This issue is fixed in version 7.22.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

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)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 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, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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
0.7%
EPSS %ILE
52nd
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 (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-13). 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, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 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, Track* at medium and Attend at high mission impact.

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 total (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)3 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 total (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 18, 2026

Advisory Details (4)

Auto-updated Sep 15, 2026
Patch available. Sources: github_pr, github_release, github, github_commit.
GitHub advisoryMentions a patch (unverified)

Content-Length + Transfer-Encoding coexistence enables request smuggling · Advisory · cesanta/mongoose · GitHub

https://github.com/cesanta/mongoose/security/advisories/GHSA-5wfq-r6mr-wqp6
GitHub release Patch Available

Mongoose 7.22

Patch available: cesanta/mongoose 7.22

https://github.com/cesanta/mongoose/releases/tag/7.22
GitHub pull request Patch Available

assorted patches

Patch available: cesanta/mongoose 7.22 (PR #3611 merged 2026-06-23)

https://github.com/cesanta/mongoose/pull/3611
GitHub commit Patch Available

commit a9df523f76f4 (cesanta/mongoose)

Patch available: cesanta/mongoose 7.22 (contains commit a9df523f76f4)

https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
mongoose7.21+ds-1, 7.21+ds-1~bpo13+1, 7.21+ds-2, 7.22+ds-1~bpo13+1
  • every version up to 7.22+ds-1: fixed in 7.22+ds-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 31× 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 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). "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 163 rows 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 63 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 17:21 UTCEchelonGraph re-scored
  2. 2026-11-13 16:57 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  3. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-11-12 16:02 UTCEchelonGraph re-scored
  5. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-11-11 15:22 UTCEchelonGraph re-scored
  7. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  8. 2026-11-10 14:44 UTCEchelonGraph re-scored
  9. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  10. 2026-11-09 14:06 UTCEchelonGraph re-scored
  11. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  12. 2026-11-08 13:28 UTCEchelonGraph re-scored
  13. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  14. 2026-11-07 12:50 UTCEchelonGraph re-scored
  15. 2026-11-06 17:25 UTCOSV refresh
  16. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  17. 2026-11-06 12:13 UTCEchelonGraph re-scored
  18. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  19. 2026-11-05 11:35 UTCEchelonGraph re-scored
  20. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  21. 2026-11-04 10:57 UTCEchelonGraph re-scored
  22. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  23. 2026-11-03 10:19 UTCEchelonGraph re-scored
  24. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-11-02 09:35 UTCEchelonGraph re-scored
Show 75 more
  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  2. 2026-11-01 08:58 UTCEchelonGraph re-scored
  3. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-10-31 08:19 UTCEchelonGraph re-scored
  5. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-10-30 07:42 UTCEchelonGraph re-scored
  7. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  8. 2026-10-29 07:04 UTCEchelonGraph re-scored
  9. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  10. 2026-10-28 06:26 UTCEchelonGraph re-scored
  11. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  12. 2026-10-27 05:49 UTCEchelonGraph re-scored
  13. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  14. 2026-10-26 01:08 UTCEchelonGraph re-scored
  15. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  16. 2026-10-25 14:06 UTCEchelonGraph re-scored
  17. 2026-10-25 00:30 UTCEchelonGraph re-scored
  18. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  19. 2026-10-23 23:52 UTCEchelonGraph re-scored
  20. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  21. 2026-10-22 23:14 UTCEchelonGraph re-scored
  22. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  23. 2026-10-21 22:36 UTCEchelonGraph re-scored
  24. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  25. 2026-10-20 21:59 UTCEchelonGraph re-scored
  26. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  27. 2026-10-19 21:21 UTCEchelonGraph re-scored
  28. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  29. 2026-10-18 16:39 UTCEchelonGraph re-scored
  30. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  31. 2026-10-18 03:15 UTCEchelonGraph re-scored
  32. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  33. 2026-10-17 15:55 UTCEchelonGraph re-scored
  34. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  35. 2026-10-16 15:18 UTCEchelonGraph re-scored
  36. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  37. 2026-10-15 14:38 UTCEchelonGraph re-scored
  38. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  39. 2026-10-14 09:14 UTCEchelonGraph re-scored
  40. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  41. 2026-10-13 06:22 UTCEchelonGraph re-scored
  42. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  43. 2026-10-12 15:41 UTCEchelonGraph re-scored
  44. 2026-10-11 19:26 UTCEchelonGraph re-scored
  45. 2026-10-11 16:42 UTCEchelonGraph re-scored
  46. 2026-10-11 14:02 UTCEchelonGraph re-scored
  47. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  48. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  49. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  50. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  51. 2026-10-08 05:22 UTCEchelonGraph re-scored
  52. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  53. 2026-10-06 16:53 UTCEchelonGraph re-scored
  54. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  55. 2026-10-05 17:55 UTCEchelonGraph re-scored
  56. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  57. 2026-10-05 01:35 UTCEchelonGraph re-scored
  58. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  59. 2026-10-03 16:47 UTCEchelonGraph re-scored
  60. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  61. 2026-10-02 19:18 UTCEchelonGraph re-scored
  62. 2026-10-01 21:29 UTCEchelonGraph re-scored
  63. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  64. 2026-09-30 20:31 UTCEchelonGraph re-scored
  65. 2026-09-29 15:46 UTCEchelonGraph re-scored
  66. 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  67. 2026-09-28 21:38 UTCEchelonGraph re-scored
  68. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  69. 2026-09-27 16:07 UTCEchelonGraph re-scored
  70. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  71. 2026-09-27 03:02 UTCEchelonGraph re-scored
  72. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  73. 2026-09-24 16:56 UTCEchelonGraph re-scored
  74. 2026-09-23 20:10 UTCEchelonGraph re-scored
  75. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 40th percentile

Frequently asked(5)

What is CVE-2026-73257?
CVE-2026-73257 is a critical-severity vulnerability; its CVE record was published on August 20, 2026. Mongoose is an embedded web server and network library. Priro to version 7.22, a remote unauthenticated attacker can send an HTTP request containing both Content-Length and Transfer-Encoding: chunked. The cl_count and te_count checks in the mg_http_parse() and http_cb() paths in src/http.c accept…
When was the CVE record for CVE-2026-73257 published?
The CVE record for CVE-2026-73257 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 18, 2026; the record at its source may have been updated since.
Is CVE-2026-73257 actively exploited?
CVE-2026-73257 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (52nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-73257?
CVE-2026-73257 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-73257?
A fix for CVE-2026-73257 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-73257

Explore →

Is Your Infrastructure Affected by CVE-2026-73257?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.