CVE-2026-53539

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-06-15. A secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-38322 (ENISA EUVD) · GHSA-5rvq-cxj2-64vf (GitHub Security Advisories) · PYSEC-2026-3036 (OSV.dev)Source: ENISA EUVD

7.5EG
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: 0.5%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for &, and only when no & existed anywhere ahead did it fall back to scanning for ;. For a body that uses ; as the separator and contains no &, every field iteration performed a full failed & scan over the entire remaining buffer before locating the nearby ;. With N semicolon separated fields in a chunk of size B, this yields O(B^2) byte comparisons per chunk. An attacker can submit a small crafted body of the form a;a;a;... and cause the parser to spend seconds of CPU per request. A handful of concurrent requests can exhaust worker processes. This vulnerability is fixed in 0.0.30.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

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)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 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
0.5%
EPSS %ILE
40th
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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-09). 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 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.

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

June 15, 2026

Last Modified

October 25, 2026

Advisory Details (1)

Auto-updated Jun 22, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

Quadratic-time querystring parsing with semicolon separators causes CPU denial of service · Advisory · Kludex/python-multipart · GitHub

https://github.com/Kludex/python-multipart/security/advisories/GHSA-5rvq-cxj2-64vf

Vendor Advisories for CVE-2026-53539(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatjaeger-main-2.19.0-1.hum12026-06-10redhat
pippython-multipart @ 0.0.30 (fixes < 0.0.30)—ghsa

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)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
python-multipart0.0.17-1 ... 0.0.9-1 (14 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
python-multipart0.0.17-1 ... 0.0.9-1 (14 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
python-multipart0.0.20-1 ... 0.0.32-1 (6 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
python-multipart0.0.20-1, 0.0.20-1.1, 0.0.20-1.1~deb13u1, 0.0.22-1, 0.0.26-1
  • every version up to 0.0.32-1: fixed in 0.0.32-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
python-multipart0.0.1 ... 0.0.9 (29 versions)
  • every version up to 0.0.30: fixed in 0.0.30
—

Weakness Classification(2)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 8× in last 7d / 32× 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 190 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 90 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  2. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  3. 2026-11-10 16:44 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  4. 2026-11-09 16:54 UTCEchelonGraph re-scored
  5. 2026-11-09 16:54 UTCGHSA enrichmentGHSA-5rvq-cxj2-64vf · GitHub severity HIGH · GitHub CVSS 7.5
  6. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  7. 2026-11-08 16:39 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  8. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.5% · 40th percentile
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  11. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  12. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  13. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  14. 2026-11-02 08:14 UTCEchelonGraph re-scored
  15. 2026-11-02 08:14 UTCGHSA enrichmentGHSA-5rvq-cxj2-64vf · GitHub severity HIGH · GitHub CVSS 7.5
  16. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  17. 2026-11-01 07:45 UTCGHSA enrichmentGHSA-5rvq-cxj2-64vf · GitHub severity HIGH · GitHub CVSS 7.5
  18. 2026-11-01 07:45 UTCEchelonGraph re-scored
  19. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  20. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  21. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  22. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  23. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  24. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  25. 2026-10-25 23:33 UTCEchelonGraph re-scored
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  1. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  2. 2026-10-25 14:20 UTCEchelonGraph re-scored
  3. 2026-10-24 17:16 UTCEchelonGraph re-scored
  4. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  5. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  6. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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  8. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  9. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  10. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  11. 2026-10-18 03:31 UTCEchelonGraph re-scored
  12. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  13. 2026-10-17 08:36 UTCEchelonGraph re-scored
  14. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  15. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  16. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  17. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  18. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  19. 2026-10-12 15:57 UTCEchelonGraph re-scored
  20. 2026-10-11 19:40 UTCEchelonGraph re-scored
  21. 2026-10-11 16:55 UTCEchelonGraph re-scored
  22. 2026-10-11 14:19 UTCEchelonGraph re-scored
  23. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  24. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  25. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  26. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  27. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  28. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  29. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  30. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  31. 2026-10-03 07:39 UTCOSV refresh
  32. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  33. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  34. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  35. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  36. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  37. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  38. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  39. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  40. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  41. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  42. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  43. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  44. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  45. 2026-09-14 03:41 UTCEchelonGraph re-scored
  46. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  47. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  48. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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  51. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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  55. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  56. 2026-08-30 22:58 UTCEchelonGraph re-scored
  57. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  58. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  59. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  60. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  61. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  62. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  63. 2026-08-24 23:32 UTCEchelonGraph re-scored
  64. 2026-08-23 09:44 UTCEchelonGraph re-scored
  65. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  66. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  67. 2026-08-21 10:10 UTCEchelonGraph re-scored
  68. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  69. 2026-08-20 08:40 UTCEchelonGraph re-scored
  70. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  71. 2026-08-19 13:14 UTCEchelonGraph re-scored
  72. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  73. 2026-08-17 15:32 UTCEchelonGraph re-scored
  74. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  75. 2026-08-17 02:38 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2026-53539?
CVE-2026-53539 is a high-severity vulnerability; its CVE record was published on June 15, 2026. Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for &, and only when no & existed anywhere ahead…
When was the CVE record for CVE-2026-53539 published?
The CVE record for CVE-2026-53539 was published on June 15, 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 25, 2026; the record at its source may have been updated since.
Is CVE-2026-53539 actively exploited?
CVE-2026-53539 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (40th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-53539?
CVE-2026-53539 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-53539?
A fix for CVE-2026-53539 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-53539 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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