CVE-2026-34988

MEDIUMNVD 6.36.3
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 6.3 under NVD CVSS v3. EPSS exploit probability: 0.3% (21st percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2026-21033 (ENISA EUVD)Source: ENISA EUVD

6.3EG
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: 0.3%CVSS: 6.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Wasmtime is a runtime for WebAssembly. From 28.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon. The pooling allocator must be in use, Config::memory_guard_size configuration option must be 0, Config::memory_reservation configuration must be less than 4GiB, and pooling allocator must be configured with max_memory_size the same as the memory_reservation value in order to exploit this vulnerability. If all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped. This represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly's semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.

CVSS v3
6.3
EG Score
6.3MEDIUMmedium confidence
EG Risk
28
EG Risk 28/100

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)
Severity63% × 45%
Impact severity (EG Severity): CVSS 6.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 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
0.3%
EPSS %ILE
21st
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 (6.3): severity, escalated by confirmed exploitation. This CVE's 6.3 is its impact severity (EG Severity), not escalated.

EG Severity
6.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). 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: 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.

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

April 9, 2026

Last Modified

October 26, 2026

Advisory Details (1)

Auto-updated Aug 2, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

Data leakage between pooling allocator instances · Advisory · bytecodealliance/wasmtime · GitHub

https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p

Affected Packages

(3 across 3 ecosystems)
crates.io(1)
PackageVulnerable rangeFix by version rangeDependents
wasmtime43.0.0
  • 28.0.0 up to 36.0.7: fixed in 36.0.7
  • 37.0.0 up to 42.0.2: fixed in 42.0.2
  • 43.0.0 up to 43.0.1: fixed in 43.0.1
  • 0.0.0-0 up to 36.0.7: fixed in 36.0.7
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
rust-wasmtime26.0.1+dfsg-10 ... 36.0.9+dfsg-2 (43 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
rust-wasmtime26.0.1+dfsg-10 ... 36.0.6+dfsg-7 (34 versions)
  • every version up to 36.0.7+dfsg-1: fixed in 36.0.7+dfsg-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 37× 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 99 of 200 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 101 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

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

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-34988?
CVE-2026-34988 is a medium-severity vulnerability; its CVE record was published on April 9, 2026. Wasmtime is a runtime for WebAssembly. From 28.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the…
When was the CVE record for CVE-2026-34988 published?
The CVE record for CVE-2026-34988 was published on April 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 October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-34988 actively exploited?
CVE-2026-34988 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (21st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-34988?
CVE-2026-34988 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-34988?
A fix for CVE-2026-34988 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-34988

Explore →

Is Your Infrastructure Affected by CVE-2026-34988?

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

Book a Demo →Browse All CVEs