CVE-2026-80431

MEDIUMPre-NVD 6.86.8
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 6.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1% (2nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-87088 (ENISA EUVD) · GHSA-fx7r-q727-j825 (GitHub Security Advisories)Source: ENISA EUVD

6.8EG
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: 0.1%CVSS: 6.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Fixed versions, as the CVE record's CNA (Secur0) states them: "Upgrade to kitty 0.49.0 or later."

Out-of-bounds Write in the natural width branch of the text sizing protocol in kitty from 0.40.0 before 0.49.0 allows a program writing to the terminal to write past the end of a fixed-size buffer, because screen_handle_multicell_command() in kitty/screen.c appends each codepoint of a grapheme cluster with lc.chars[lc.count++] = ch without any capacity check, while lc is declared by the RAII_ListOfChars macro as a four-element char_type array in the function's stack frame, so an OSC 66 escape code whose payload carries a grapheme cluster longer than four codepoints writes beyond that buffer, one 32-bit value per additional codepoint, in the order the codepoints appear. Where the cluster is preceded in the same payload by a sequence that causes an intermediate flush, the buffer is first migrated to the heap by ensure_space_for_chars() and the write occurs past the heap allocation instead. This results in termination of the kitty process and therefore of all its windows, tabs and child processes.

CVSS
6.8
EG Score
6.8MEDIUMmedium confidence
EG Risk
31
EG Risk 31/100

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)
Severity68% × 45%
Impact severity (EG Severity): CVSS 6.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.1% × 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 every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
0.1%
EPSS %ILE
2nd
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 (6.8): severity, escalated by confirmed exploitation. This CVE's 6.8 is its impact severity (EG Severity), not escalated.

EG Severity
6.8 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-07). 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 every mission impact level.CISA BOD 26-04: 60 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 every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 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 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

September 25, 2026

Last Modified

September 29, 2026

Advisory Details (3)

Auto-updated Sep 25, 2026
Patch available. Sources: github_commit, github_release.
Web page

CVE-2026-80431 · Out-of-bounds write in the kitty text sizing protocol allows termination of the terminal process | Vulnerabilities published by Secur0

https://secur0.com/en/cna/cve-list/cve-2026-80431-kitty-text-sizing-out-of-bounds-write
GitHub release Patch Available

version 0.49.0

Patch available: kovidgoyal/kitty v0.49.0

https://github.com/kovidgoyal/kitty/releases/tag/v0.49.0
GitHub commit

commit 7d2fbaadcc2b (kovidgoyal/kitty)

Fix landed in kovidgoyal/kitty commit 7d2fbaadcc2b — awaiting tagged release

https://github.com/kovidgoyal/kitty/commit/7d2fbaadcc2b1eeeef89bd875ec622b42362574b

Vendor Advisories for CVE-2026-80431(1)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
kitty0.26.5-5 ... 0.48.2-1.1 (40 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
kitty0.41.1-2 ... 0.48.2-1.1 (18 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
kitty0.41.1-2 ... 0.48.2-1.1 (16 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 33× 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 → 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.

  1. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  2. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  3. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  4. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  5. 2026-11-08 16:41 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  6. 2026-11-07 19:18 UTCGHSA enrichmentGHSA-fx7r-q727-j825 · GitHub severity MODERATE
  7. 2026-11-07 19:18 UTCEchelonGraph re-scored
  8. 2026-11-07 16:40 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  9. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  10. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  11. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  12. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  13. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  14. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  15. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  16. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  17. 2026-10-30 02:25 UTCOSV refresh
  18. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  19. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  20. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  21. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  22. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  23. 2026-10-25 13:59 UTCEchelonGraph re-scored
  24. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  25. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
Show 69 more
  1. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  2. 2026-10-22 13:54 UTCEchelonGraph re-scored
  3. 2026-10-22 13:54 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  4. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  5. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  6. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  7. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  8. 2026-10-18 03:10 UTCEchelonGraph re-scored
  9. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  10. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  11. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  12. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  13. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  14. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  15. 2026-10-12 14:57 UTCEchelonGraph re-scored
  16. 2026-10-12 01:58 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  17. 2026-10-11 19:21 UTCEchelonGraph re-scored
  18. 2026-10-11 16:37 UTCEchelonGraph re-scored
  19. 2026-10-11 13:55 UTCEchelonGraph re-scored
  20. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  21. 2026-10-11 03:32 UTCEchelonGraph re-scored
  22. 2026-10-11 03:32 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  23. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  24. 2026-10-10 04:56 UTCEchelonGraph re-scored
  25. 2026-10-10 04:55 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  26. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  27. 2026-10-09 06:30 UTCEchelonGraph re-scored
  28. 2026-10-09 06:30 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  29. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  30. 2026-10-08 08:05 UTCEchelonGraph re-scored
  31. 2026-10-08 08:05 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  32. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  33. 2026-10-07 09:38 UTCEchelonGraph re-scored
  34. 2026-10-07 09:38 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  35. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  36. 2026-10-06 11:13 UTCEchelonGraph re-scored
  37. 2026-10-06 11:13 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  38. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  39. 2026-10-05 12:49 UTCEchelonGraph re-scored
  40. 2026-10-05 12:48 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  41. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  42. 2026-10-04 14:24 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  43. 2026-10-03 15:59 UTCEchelonGraph re-scored
  44. 2026-10-03 15:59 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  45. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  46. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  47. 2026-10-02 17:33 UTCEchelonGraph re-scored
  48. 2026-10-02 17:33 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  49. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  50. 2026-10-01 19:07 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  51. 2026-09-30 20:42 UTCEchelonGraph re-scored
  52. 2026-09-30 20:42 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  53. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  54. 2026-09-29 22:18 UTCEchelonGraph re-scored
  55. 2026-09-29 22:17 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  56. 2026-09-29 10:15 UTCEchelonGraph re-scored
  57. 2026-09-29 10:15 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  58. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  59. 2026-09-28 11:44 UTCEchelonGraph re-scored
  60. 2026-09-28 11:44 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  61. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  62. 2026-09-27 13:19 UTCEchelonGraph re-scored
  63. 2026-09-27 13:19 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  64. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  65. 2026-09-26 14:54 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  66. 2026-09-25 16:27 UTCGHSA enrichmentGHSA-fx7r-q727-j825
  67. 2026-09-25 14:22 UTCEchelonGraph re-scored
  68. 2026-09-25 13:36 UTCEchelonGraph re-scoredFirst assessed: 6.8 MEDIUM
  69. 2026-09-25 13:34 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-80431?
CVE-2026-80431 is a medium-severity vulnerability; its CVE record was published on September 25, 2026. Out-of-bounds Write in the natural width branch of the text sizing protocol in kitty from 0.40.0 before 0.49.0 allows a program writing to the terminal to write past the end of a fixed-size buffer, because screen_handle_multicell_command() in kitty/screen.c appends each codepoint of a grapheme…
When was CVE-2026-80431 made public?
CVE-2026-80431 was made public on September 21, 2026: that is the date its CVE record's CNA, Secur0, gives for when the vulnerability was made public. The CVE record itself was published on September 25, 2026. EchelonGraph's copy of the record carries a last-modified date of September 29, 2026; the record at its source may have been updated since.
Is CVE-2026-80431 actively exploited?
CVE-2026-80431 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (2nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-80431?
CVE-2026-80431 has a CVSS base score of 6.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-80431?
A fix for CVE-2026-80431 is available: update to the fixed version the vendor names in its advisory. Fixed versions, as the CVE record's CNA (Secur0) states them: "Upgrade to kitty 0.49.0 or later." The vendor advisories EchelonGraph has for CVE-2026-80431 are linked in the Vendor Advisories panel on this page.

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