CVE-2026-15308

HIGHNVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-09. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
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: 0.6%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.

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 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 (value × EchelonGraph’s weight)
Severity75% × 45%
The EG Score, 7.5 of 10.
Exploitation0.6% × 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
0.6%
EPSS %ILE
49th
KEV
Not listed

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

July 9, 2026

Last Modified

August 20, 2026

Advisory Details (3)

Auto-updated Jul 9, 2026
Patch available. Sources: github_pr.
Web page

Mailman 3 [CVE-2026-15308] Incremental HTMLParser allows CPU-exhaustion DoS via repeated unterminated markup declarations - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5/
GitHub pull request

gh-153030: Fix quadratic complexity in incremental parsing in HTMLParser

Fix merged in python/cpython PR #153031 on 2026-07-04 — awaiting tagged release

https://github.com/python/cpython/pull/153031
Web page

Another worst case quadratic complexity in HTMLParser · Issue #153030 · python/cpython · GitHub

https://github.com/python/cpython/issues/153030

Vendor Advisories for CVE-2026-15308(20)

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

Patch Availability(30)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntupython3.5-venv (3.5.2-2ubuntu0~16.04.13+esm25) @ xenial2026-10-01ubuntu
redhatrhai/base-image-rocm-rhel9:17902768862026-09-30redhat
redhatrhai/base-image-cuda-rhel9:17902769742026-09-30redhat
redhatpython3.9-0:3.9.21-2.el9_6.72026-09-30redhat
redhatrhai/base-image-spyre-rhel9:17902768892026-09-30redhat
redhatrhai/base-image-tpu-rhel9:17902768842026-09-30redhat
redhatrhai/base-image-cpu-rhel9:17902770452026-09-30redhat
redhatpython3.9-0:3.9.18-3.el9_4.142026-09-30redhat
redhatrhui5/rhua-tp-rhel9:17872412602026-08-24redhat
redhatpython3-14-main-3.14.7-1.hum12026-08-13redhat
redhatpython3-13-main-3.13.15-1.hum12026-08-13redhat
redhatpython3.12-0:3.12.9-1.el9_6.92026-08-05redhat
redhatpython3.12-0:3.12.1-4.el9_4.142026-08-05redhat
redhatpython3-0:3.6.8-39.el8_4.122026-08-05redhat
redhatpython3-0:3.6.8-47.el8_6.142026-08-04redhat
redhatpython3-0:3.6.8-51.el8_8.162026-08-04redhat
redhatpython3.12-0:3.12.9-2.el10_0.102026-07-29redhat
redhatdiscovery/discovery-ui-rhel9:17848217502026-07-27redhat
redhatrhui5/rhua-rhel9:17847950762026-07-23redhat
redhatpython3.14-0:3.14.5-1.el9_8.12026-07-20redhat
redhatpython3.14-0:3.14.5-1.el10_2.12026-07-16redhat
redhatpython3.12-0:3.12.13-3.el9_8.12026-07-15redhat
redhatpython3.12-0:3.12.13-3.el8_102026-07-15redhat
redhatpython3.9-0:3.9.25-7.el9_8.22026-07-15redhat
redhatpython3.12-0:3.12.13-2.el10_2.12026-07-14redhat
redhatpython3-0:3.6.8-77.el8_102026-07-14redhat
redhatpython3-11-main-3.11.15-5.2.hum12026-07-10redhat
redhatpython3-14-main-3.14.6-1.3.hum12026-07-10redhat
redhatpython3-13-main-3.13.14-1.3.hum12026-07-10redhat
redhatpython3-12-main-3.12.13-3.5.hum12026-07-10redhat

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

(10 across 8 ecosystems)
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
python2.72.7.18-10 ... 2.7.18-9 (10 versions)
  • every version on: no fix on record
—
python3.93.9.10-1 ... 3.9.9-4 (29 versions)
  • every version on: no fix on record
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
python3.133.13.11-1 ... 3.13.9-1 (8 versions)
  • every version up to 3.13.15-1: fixed in 3.13.15-1
—
python3.143.14.0-1 ... 3.14.6-1 (24 versions)
  • every version up to 3.14.7-1: fixed in 3.14.7-1
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.14-r0: fixed in 3.12.14-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.14-r0: fixed in 3.12.14-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.14-r0: fixed in 3.12.14-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.14.7-r0: fixed in 3.14.7-r0
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
python3.113.11.2-6 ... 3.11.2-6+deb12u8 (9 versions)
  • every version up to 3.11.2-6+deb12u9: fixed in 3.11.2-6+deb12u9
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
python3.133.13.11-1 ... 3.13.9-1 (14 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

All Vendor Advisories

(25)

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 11× in last 7d / 39× 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 340 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 240 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  2. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  3. 2026-10-12 16:32 UTCEG score recompute
  4. 2026-10-11 20:10 UTCEG score recompute
  5. 2026-10-11 17:22 UTCEG score recompute
  6. 2026-10-11 14:55 UTCEG score recompute
  7. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  8. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  9. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  10. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  11. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  12. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  13. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  14. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  15. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  16. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  17. 2026-10-01 16:02 UTCEG score recompute
  18. 2026-10-01 16:02 UTCVendor advisory
  19. 2026-10-01 16:02 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  20. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  21. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  22. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  23. 2026-09-28 10:28 UTCEG score recompute
  24. 2026-09-28 10:28 UTCVendor advisory
  25. 2026-09-28 10:28 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
Show 75 more
  1. 2026-09-27 13:47 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  2. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  3. 2026-09-24 11:24 UTCEG score recompute
  4. 2026-09-24 11:24 UTCVendor advisory
  5. 2026-09-24 11:24 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  6. 2026-09-23 05:54 UTCEG score recompute
  7. 2026-09-23 05:54 UTCVendor advisory
  8. 2026-09-23 05:54 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  9. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  10. 2026-09-18 05:36 UTCEG score recompute
  11. 2026-09-18 05:36 UTCVendor advisory
  12. 2026-09-18 05:36 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  13. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  14. 2026-09-16 05:14 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  15. 2026-09-14 11:20 UTCVendor advisory
  16. 2026-09-14 11:20 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  17. 2026-09-13 23:46 UTCEG score recompute
  18. 2026-09-13 23:46 UTCVendor advisory
  19. 2026-09-13 23:46 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  20. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  21. 2026-09-13 08:18 UTCEG score recompute
  22. 2026-09-13 08:18 UTCVendor advisory
  23. 2026-09-13 08:18 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  24. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  25. 2026-09-12 14:58 UTCVendor advisory
  26. 2026-09-12 14:58 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  27. 2026-09-12 03:23 UTCEG score recompute
  28. 2026-09-12 03:23 UTCVendor advisory
  29. 2026-09-12 03:23 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  30. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  31. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  32. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  33. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  34. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  35. 2026-09-06 13:59 UTCEG score recompute
  36. 2026-09-06 13:59 UTCVendor advisory
  37. 2026-09-06 13:59 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  38. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  39. 2026-09-05 22:35 UTCEG score recompute
  40. 2026-09-05 22:35 UTCVendor advisory
  41. 2026-09-05 22:34 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  42. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  43. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  44. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  45. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  46. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  47. 2026-08-30 18:20 UTCVendor advisory
  48. 2026-08-30 18:20 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  49. 2026-08-30 06:45 UTCEG score recompute
  50. 2026-08-30 06:45 UTCVendor advisory
  51. 2026-08-30 06:45 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  52. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  53. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  54. 2026-08-27 21:45 UTCEG score recompute
  55. 2026-08-27 21:45 UTCVendor advisory
  56. 2026-08-27 21:45 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  57. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  58. 2026-08-27 01:01 UTCEG score recompute
  59. 2026-08-27 01:01 UTCVendor advisory
  60. 2026-08-27 01:00 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  61. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  62. 2026-08-26 03:50 UTCEG score recompute
  63. 2026-08-26 03:50 UTCVendor advisory
  64. 2026-08-26 03:50 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  65. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  66. 2026-08-25 07:55 UTCVendor advisory
  67. 2026-08-25 07:55 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  68. 2026-08-24 20:20 UTCEG score recompute
  69. 2026-08-24 20:20 UTCVendor advisory
  70. 2026-08-24 20:20 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  71. 2026-08-24 04:15 UTCVendor advisory
  72. 2026-08-24 04:15 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  73. 2026-08-23 16:40 UTCVendor advisory
  74. 2026-08-23 16:40 UTCGHSA enrichmentGHSA-7qj2-q5c8-cxx5 · GitHub severity CRITICAL · GitHub CVSS 7.5
  75. 2026-08-23 05:06 UTCEG score recompute

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-15308?
CVE-2026-15308 is a high-severity vulnerability; its CVE record was published on July 9, 2026. The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.
When was the CVE record for CVE-2026-15308 published?
The CVE record for CVE-2026-15308 was published on July 9, 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 August 20, 2026; the record at its source may have been updated since.
Is CVE-2026-15308 actively exploited?
CVE-2026-15308 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (49th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-15308?
CVE-2026-15308 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-15308?
A fix for CVE-2026-15308 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-15308 are linked in the Vendor Advisories panel on this page.

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