CVE-2026-77088

MEDIUMPre-NVD 6.16.1
EchelonGraph scoreMEDIUM confidence

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

Score 6.1 from GitHub Security Advisory published 2026-08-23. A secondary CVSS source baseline 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this week
6.1EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 6.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

justhtml versions 0.9.0 through 1.21.0 contain a cross-site scripting vulnerability in to_markdown() where inline code spans fail to account for blank lines as block boundaries. Attackers can inject blank lines into code or pre element text to break the inline span, causing sanitized HTML to be emitted unescaped and re-parsed as live Markdown by compliant renderers.

CVSS v3
6.1
EG Score
6.1MEDIUMmedium confidence
EG Risk
43
EG Risk 43/100

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)
Severity61% × 45%
The EG Score, 6.1 of 10.
Exploitation0.3% × 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
0.3%
EPSS %ILE
16th
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

August 23, 2026

Last Modified

October 12, 2026

Advisory Details (2)

Auto-updated Aug 23, 2026
Patch available. Sources: github.
Web page

justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span | Advisories | VulnCheck

https://www.vulncheck.com/advisories/justhtml-through-cross-site-scripting-via-code-span
GitHub advisoryMentions a patch (unverified)

justhtml: to_markdown() code-span blank-line breakout enables XSS · Advisory · EmilStenstrom/justhtml · GitHub

https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-jf6w-2mvx-633j

Vendor Advisories for CVE-2026-77088(1)

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

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
justhtml0.10.0 ... 1.9.1 (56 versions)
  • 0.9.0 up to 1.22.0: fixed in 1.22.0
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 75× 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 136 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 36 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  3. 2026-10-12 16:32 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  4. 2026-10-12 15:37 UTCEG score recompute
  5. 2026-10-11 19:23 UTCEG score recompute
  6. 2026-10-11 16:39 UTCEG score recompute
  7. 2026-10-11 13:58 UTCEG score recompute
  8. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  9. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  10. 2026-10-10 14:12 UTCEG score recompute
  11. 2026-10-10 14:12 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  12. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  13. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  14. 2026-10-08 07:48 UTCEG score recompute
  15. 2026-10-08 07:48 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  16. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  17. 2026-10-07 05:23 UTCEG score recompute
  18. 2026-10-07 05:23 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  19. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  20. 2026-10-06 02:58 UTCEG score recompute
  21. 2026-10-06 02:58 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  22. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  23. 2026-10-04 20:45 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  24. 2026-10-03 16:34 UTCEG score recompute
  25. 2026-10-03 16:34 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
Show 75 more
  1. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  2. 2026-10-02 13:21 UTCEG score recompute
  3. 2026-10-02 13:21 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  4. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  5. 2026-10-01 10:43 UTCEG score recompute
  6. 2026-10-01 10:42 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  7. 2026-09-30 08:07 UTCEG score recompute
  8. 2026-09-30 08:07 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  9. 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  10. 2026-09-29 05:42 UTCEG score recompute
  11. 2026-09-29 05:42 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  12. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  13. 2026-09-28 03:17 UTCEG score recompute
  14. 2026-09-28 03:17 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  15. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  16. 2026-09-27 00:52 UTCEG score recompute
  17. 2026-09-27 00:52 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  18. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  19. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  20. 2026-09-25 16:55 UTCEG score recompute
  21. 2026-09-25 16:55 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  22. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  23. 2026-09-24 12:54 UTCEG score recompute
  24. 2026-09-24 12:54 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  25. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  26. 2026-09-23 10:29 UTCEG score recompute
  27. 2026-09-23 10:29 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  28. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  29. 2026-09-22 08:04 UTCEG score recompute
  30. 2026-09-22 08:04 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  31. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  32. 2026-09-21 05:40 UTCEG score recompute
  33. 2026-09-21 05:40 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  34. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  35. 2026-09-20 02:56 UTCEG score recompute
  36. 2026-09-20 02:56 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  37. 2026-09-19 00:31 UTCEG score recompute
  38. 2026-09-19 00:31 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  39. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  40. 2026-09-17 22:04 UTCEG score recompute
  41. 2026-09-17 22:04 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  42. 2026-09-16 19:39 UTCEG score recompute
  43. 2026-09-16 19:39 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  44. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  45. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  46. 2026-09-15 16:15 UTCEG score recompute
  47. 2026-09-15 16:15 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  48. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  49. 2026-09-14 13:50 UTCEG score recompute
  50. 2026-09-14 13:50 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  51. 2026-09-13 11:26 UTCEG score recompute
  52. 2026-09-13 11:26 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  53. 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  54. 2026-09-12 09:02 UTCEG score recompute
  55. 2026-09-12 09:02 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  56. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  57. 2026-09-11 06:37 UTCEG score recompute
  58. 2026-09-11 06:37 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  59. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  60. 2026-09-10 04:12 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  61. 2026-09-09 01:36 UTCEG score recompute
  62. 2026-09-09 01:36 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  63. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  64. 2026-09-07 08:33 UTCEG score recompute
  65. 2026-09-07 08:33 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  66. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  67. 2026-09-06 05:56 UTCEG score recompute
  68. 2026-09-06 05:56 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  69. 2026-09-05 03:32 UTCEG score recompute
  70. 2026-09-05 03:32 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  71. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  72. 2026-09-04 01:07 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  73. 2026-09-02 22:40 UTCEG score recompute
  74. 2026-09-02 22:40 UTCGHSA enrichmentGHSA-3r4x-v5v7-fm2r · GitHub CVSS 6.1
  75. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 8th percentile

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-77088?
CVE-2026-77088 is a medium-severity vulnerability; its CVE record was published on August 23, 2026. justhtml versions 0.9.0 through 1.21.0 contain a cross-site scripting vulnerability in to_markdown() where inline code spans fail to account for blank lines as block boundaries. Attackers can inject blank lines into code or pre element text to break the inline span, causing sanitized HTML to be…
When was CVE-2026-77088 made public?
CVE-2026-77088 was made public on May 22, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on August 23, 2026. EchelonGraph's copy of the record carries a last-modified date of October 12, 2026; the record at its source may have been updated since.
Is CVE-2026-77088 actively exploited?
CVE-2026-77088 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (16th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-77088?
CVE-2026-77088 has a CVSS base score of 6.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-77088?
A fix for CVE-2026-77088 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-77088 are linked in the Vendor Advisories panel on this page.

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