CVE-2026-77912

MEDIUMNVD 5.45.4
EchelonGraph scoreMEDIUM confidence

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

Score 5.4 from GitHub Security Advisory (severity: HIGH) published 2026-09-22. NVD baseline CVSS 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-84873 (ENISA EUVD) · GHSA-6293-4rx2-2p57 (GitHub Security Advisories)Source: ENISA EUVD

5.4EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.4Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

A stored cross-site scripting (XSS) vulnerability was identified in GitHub Enterprise Server that allowed an authenticated attacker to inject arbitrary HTML attributes into rendered Markdown because the Markdown rendering pipeline rewrote quote characters in already-sanitized HTML without re-sanitizing the result. Crafted Markdown could abuse same-origin JavaScript gadgets to bypass Content Security Policy and gain control of the page DOM when viewed by another user. Successful exploitation could allow an attacker to read content visible to the victim, extract embedded CSRF tokens, perform state-changing actions as the victim, and exfiltrate data through same-origin writes. The payload could also propagate to repositories and organizations where the victim had write access. This vulnerability affected supported GitHub Enterprise Server releases in the 3.17, 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.22.1, 3.21.6, 3.20.8, 3.19.12, 3.18.15, and 3.17.21. This vulnerability was reported via the GitHub Bug Bounty program.

CVSS v3
5.4
EG Score
5.4MEDIUMmedium confidence
EG Risk
24
EG Risk 24/100

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)
Severity54% × 45%
Impact severity (EG Severity): CVSS 5.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (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: The CVE record names the fixed release. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
10th
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 (5.4): severity, escalated by confirmed exploitation. This CVE's 5.4 is its impact severity (EG Severity), not escalated.

EG Severity
5.4 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade 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; Track* at high (mission-essential systems).

The CVE record names the fixed release. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (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

September 22, 2026

Last Modified

October 2, 2026

Advisory Details (6)

Auto-updated Sep 22, 2026
Fix named in the CVE record.
Web page

Release notes - GitHub Enterprise Server 3.22 Docs

https://docs.github.com/en/[email protected]/admin/release-notes#3.22.1
Web page

Release notes - GitHub Enterprise Server 3.21 Docs

https://docs.github.com/en/[email protected]/admin/release-notes#3.21.6
Web page

Release notes - GitHub Enterprise Server 3.20 Docs

https://docs.github.com/en/[email protected]/admin/release-notes#3.20.8
Web page

Release notes - GitHub Enterprise Server 3.19 Docs

https://docs.github.com/en/[email protected]/admin/release-notes#3.19.12
Web page

Release notes - GitHub Enterprise Server 3.18 Docs

https://docs.github.com/en/[email protected]/admin/release-notes#3.18.15
Web page

Release notes - GitHub Enterprise Server 3.17 Docs

https://docs.github.com/en/[email protected]/admin/release-notes#3.17.21

Vendor Advisories for CVE-2026-77912(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 30× 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 109 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 9 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 0.2% · 10th percentile
  2. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  3. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  4. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  5. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  6. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  7. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  8. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  9. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  10. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  11. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  12. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  13. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  14. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  15. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  16. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  17. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  18. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  19. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  20. 2026-10-25 14:01 UTCEchelonGraph re-scored
  21. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  22. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  23. 2026-10-22 21:34 UTCEchelonGraph re-scored
  24. 2026-10-22 21:34 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  25. 2026-10-22 18:20 UTCEchelonGraph re-scored
Show 75 more
  1. 2026-10-22 18:20 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  2. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  3. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  4. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  5. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  6. 2026-10-18 03:11 UTCEchelonGraph re-scored
  7. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  8. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  9. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  10. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  11. 2026-10-12 15:37 UTCEchelonGraph re-scored
  12. 2026-10-11 19:23 UTCEchelonGraph re-scored
  13. 2026-10-11 16:39 UTCEchelonGraph re-scored
  14. 2026-10-11 14:49 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  15. 2026-10-11 13:57 UTCEchelonGraph re-scored
  16. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  17. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  18. 2026-10-10 15:42 UTCEchelonGraph re-scored
  19. 2026-10-10 15:42 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  20. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  21. 2026-10-09 16:19 UTCEchelonGraph re-scored
  22. 2026-10-09 16:19 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  23. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  24. 2026-10-08 17:11 UTCEchelonGraph re-scored
  25. 2026-10-08 17:10 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  26. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  27. 2026-10-07 14:51 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  28. 2026-10-06 15:41 UTCEchelonGraph re-scored
  29. 2026-10-06 15:41 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  30. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  31. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  32. 2026-10-05 16:11 UTCEchelonGraph re-scored
  33. 2026-10-05 16:11 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  34. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  35. 2026-10-04 16:58 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  36. 2026-10-03 17:50 UTCEchelonGraph re-scored
  37. 2026-10-03 17:50 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH · GitHub CVSS 5.4
  38. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  39. 2026-10-02 18:42 UTCEchelonGraph re-scored▼ 2.00
  40. 2026-10-02 18:42 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  41. 2026-10-02 18:39 UTCNVD updateCVSS v3 → 5.4 · severity → MEDIUM
  42. 2026-10-02 06:58 UTCEchelonGraph re-scored
  43. 2026-10-02 06:58 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  44. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  45. 2026-10-01 18:24 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  46. 2026-10-01 05:21 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  47. 2026-09-30 16:46 UTCEchelonGraph re-scored
  48. 2026-09-30 16:46 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  49. 2026-09-30 03:15 UTCEchelonGraph re-scored
  50. 2026-09-30 03:15 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  51. 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  52. 2026-09-29 14:40 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  53. 2026-09-29 02:04 UTCEchelonGraph re-scored
  54. 2026-09-29 02:04 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  55. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  56. 2026-09-28 13:30 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  57. 2026-09-28 00:55 UTCEchelonGraph re-scored
  58. 2026-09-28 00:55 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  59. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  60. 2026-09-27 12:20 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  61. 2026-09-26 23:45 UTCEchelonGraph re-scored
  62. 2026-09-26 23:45 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  63. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  64. 2026-09-26 11:11 UTCEchelonGraph re-scored
  65. 2026-09-26 11:10 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  66. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  67. 2026-09-25 22:33 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  68. 2026-09-25 09:57 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  69. 2026-09-24 21:22 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  70. 2026-09-24 16:38 UTCEchelonGraph re-scored
  71. 2026-09-24 16:38 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  72. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  73. 2026-09-24 03:55 UTCEchelonGraph re-scored
  74. 2026-09-24 03:55 UTCGHSA enrichmentGHSA-6293-4rx2-2p57 · GitHub severity HIGH
  75. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 38th percentile

Frequently asked(5)

What is CVE-2026-77912?
CVE-2026-77912 is a medium-severity vulnerability; its CVE record was published on September 22, 2026. A stored cross-site scripting (XSS) vulnerability was identified in GitHub Enterprise Server that allowed an authenticated attacker to inject arbitrary HTML attributes into rendered Markdown because the Markdown rendering pipeline rewrote quote characters in already-sanitized HTML without…
When was the CVE record for CVE-2026-77912 published?
The CVE record for CVE-2026-77912 was published on September 22, 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 2, 2026; the record at its source may have been updated since.
Is CVE-2026-77912 actively exploited?
CVE-2026-77912 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (10th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-77912?
CVE-2026-77912 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-77912?
The CVE record for CVE-2026-77912 names the fix: "This vulnerability affected supported GitHub Enterprise Server releases in the 3.17, 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.22.1, 3.21.6, 3.20.8, 3.19.12, 3.18.15, and 3.17.21." The vendor advisories EchelonGraph has for CVE-2026-77912 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-77912

Explore →

Is Your Infrastructure Affected by CVE-2026-77912?

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