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TI-2020-20049 Aliases CVE-2020-37288

Vyper return in nested loops causes invalid jump destination

Priority LOW 28CWE-670Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
None · None · Low
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Vyper from 0.1.0b10 before 0.2.3 generates incorrect code for a return statement inside a for loop in an internal function called two or more internal calls deep, producing an invalid jump destination (CWE-670). An unauthenticated remote attacker can make affected contracts revert such calls unnecessarily, which in limited circumstances could enable denial of service against public contracts.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

Description from the CNA

Vyper from 0.1.0b10 before 0.2.3 generates incorrect code for a return statement inside a for loop in an internal function called two or more internal calls deep, producing an invalid jump destination (stack underflow). Affected contracts revert such calls unnecessarily, which in limited circumstances could enable denial of service against public contracts.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00347 28th percentileScored 2026-11-07
Fix Fixed vyper (vyperlang): 0.2.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
vyperlangvyper0.1.0b10 to before 0.2.30.2.3Patch availableCNA
  • vyper Vendorvyperlang Affected 0.1.0b10 to before 0.2.3 Fixed in 0.2.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:vyperlang:vyper:*:*:*:*:*:*:*:*——vyperlang
  • cpe:2.3:a:vyperlang:vyper:*:*:*:*:*:*:*:* Versions — — ·vyperlang

Remediation

Vyper 0.2.3 fixes this flaw, so update affected Vyper releases to 0.2.3.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

  • Fix · CNA vyper (vyperlang) Fixed in 0.2.3

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-21 Threatist record created from CVE-2020-37288
  2. 2026-10-21 CISA SSVC decision points changed
  3. 2026-10-21 Priority changed: MEDIUM → LOW
  4. 2026-11-03 Affected versions changed · Red Hat
  5. 2026-11-03 CVSS score added · Red Hat

References

Advisory 1

  • TI-2024-16182 Vyper bounds check on built-in `slice()` function can be overflowed CVSS 3.1CRITICAL 9.8
  • TI-2024-14992 concat built-in can corrupt memory in vyper CVSS 3.1CRITICAL 9.8
  • TI-2024-16184 Vyper array negative index vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2022-08657 Integer bounds error in Vyper CVSS 3.1CRITICAL 9.8
  • TI-2022-11796 Multiple evaluation of contract address in call in vyper CVSS 3.1HIGH 8.2
  • TI-2026-78730 Optimizer miscompilation of msg.value | K in Vyper ternary branches CVSS 4.0HIGH 8.2
See all 52 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences