CVE-2026-15308

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

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, ghsa, nvd
Trending — 4 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

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
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

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
Severity75% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
49%
KEV
Not listed

Published

July 9, 2026

Last Modified

August 20, 2026

Advisory Details (3)

Auto-updated Jul 9, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
generic

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_pr

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
generic

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(23)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython3.5-venv (3.5.2-2ubuntu0~16.04.4~14.04.1+esm11) @ trusty2026-09-18ubuntu
redhatrhui5/rhua-tp-rhel9:17872412602026-08-24redhat
redhatpython3-13-main-3.13.15-1.hum12026-08-13redhat
redhatpython3-14-main-3.14.7-1.hum12026-08-13redhat
redhatpython3-0:3.6.8-39.el8_4.122026-08-05redhat
redhatpython3.12-0:3.12.9-1.el9_6.92026-08-05redhat
redhatpython3.12-0:3.12.1-4.el9_4.142026-08-05redhat
redhatpython3-0:3.6.8-51.el8_8.162026-08-04redhat
redhatpython3-0:3.6.8-47.el8_6.142026-08-04redhat
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
redhatpython3.9-0:3.9.25-7.el9_8.22026-07-15redhat
redhatpython3.12-0:3.12.13-3.el8_102026-07-15redhat
redhatpython3.12-0:3.12.13-3.el9_8.12026-07-15redhat
redhatpython3.12-0:3.12.13-2.el10_2.12026-07-14redhat
redhatpython3-0:3.6.8-77.el8_102026-07-14redhat
redhatpython3-12-main-3.12.13-3.5.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
redhatpython3-11-main-3.11.15-5.2.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 rangeFixed inDependents
python2.72.7.18-10 ... 2.7.18-9 (10 versions)——
python3.93.9.10-1 ... 3.9.9-4 (29 versions)——
Debian:14(2)
PackageVulnerable rangeFixed inDependents
python3.133.13.11-1 ... 3.13.9-1 (8 versions)3.13.15-1—
python3.143.14.0-1 ... 3.14.6-1 (24 versions)3.14.7-1—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
python3—3.12.14-r0—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
python3—3.12.14-r0—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
python3—3.12.14-r0—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
python3—3.14.7-r0—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
python3.113.11.2-6 ... 3.11.9-1 (28 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
python3.133.13.11-1 ... 3.13.9-1 (13 versions)——

Weakness Classification(1)

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

Additional Vendor Advisories

(4)

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 18× in last 7d / 86× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 307 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-15308?
CVE-2026-15308 is a high vulnerability 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 CVE-2026-15308 disclosed?
CVE-2026-15308 was first published in the National Vulnerability Database on July 9, 2026, with the most recent update on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-15308 actively exploited?
CVE-2026-15308 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 50.9% of all 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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-15308, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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