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CVE-2020-15163

Invalid root may become trusted root in The Update Framework (TUF)

8.7 HighFix available

Python TUF (The Update Framework) reference implementation before version 0.12 it will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a person-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates. This is fixed in version 0.12 and newer.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.67%Down 0.6 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 8.7

Invalid root may become trusted root in The Update Framework (TUF)

Python TUF (The Update Framework) reference implementation before version 0.12 it will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a person-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates. This is fixed in version 0.12 and newer.

Record
CVE-2020-15163
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Weakness
CWE-863
Updated
2026-11-02
EUVDEUVD-2020-0224 8.7

Python TUF (The Update Framework) reference implementation before version 0.12 it will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a person-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates. This is fixed in version 0.12 and newer.

Record
EUVD-2020-0224
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-f8mr-jv2c-v8mg 6.3

Invalid root may become trusted root in The Update Framework (TUF)

Impact

The Python TUF reference implementation tuf<0.12 will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a man-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates.

While investigating the reported vulnerability, we discovered that the detailed client workflow was not fully implemented. Specifically, for step 1.3 the newly downloaded root metadata was not being verified with a threshold of keys specified in the new root metadata file. This missing step of the client workflow has been implemented in PR #1101, which is included in v0.14.0 of tuf.

Patches

A fix, is available in version 0.12 and newer.

Workarounds

No workarounds are known for this issue.

References

  • Pull request resolving the invalid root becoming trusted issue PR 885
  • Pull request implementing self verification of newly downloaded root metadata PR 1101
Record
GHSA-f8mr-jv2c-v8mg
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Weakness
CWE-345, CWE-863
Updated
2026-11-02
NVD 8.7

Python TUF (The Update Framework) reference implementation before version 0.12 it will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a person-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates. This is fixed in version 0.12 and newer.

Record
CVE-2020-15163
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
CVSS 2.0
4.9 MediumAV:N/AC:M/Au:S/C:P/I:P/A:N
Weakness
CWE-863, CWE-345
Updated
2026-11-02
OSV 8.2

Python TUF (The Update Framework) reference implementation before version 0.12 it will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a person-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates. This is fixed in version 0.12 and newer.

Record
CVE-2020-15163
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Updated
2026-11-02
OSVGHSA-f8mr-jv2c-v8mg 6.3

Invalid root may become trusted root in The Update Framework (TUF)

Impact

The Python TUF reference implementation tuf<0.12 will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a man-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates.

While investigating the reported vulnerability, we discovered that the detailed client workflow was not fully implemented. Specifically, for step 1.3 the newly downloaded root metadata was not being verified with a threshold of keys specified in the new root metadata file. This missing step of the client workflow has been implemented in PR #1101, which is included in v0.14.0 of tuf.

Patches

A fix, is available in version 0.12 and newer.

Workarounds

No workarounds are known for this issue.

References

  • Pull request resolving the invalid root becoming trusted issue PR 885
  • Pull request implementing self verification of newly downloaded root metadata PR 1101
Record
GHSA-f8mr-jv2c-v8mg
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
CVSS 3.1
8.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Weakness
CWE-345, CWE-863
Updated
2026-11-02
OSVPYSEC-2020-145 No score

Python TUF (The Update Framework) reference implementation before version 0.12 it will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a person-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates. This is fixed in version 0.12 and newer.

Record
PYSEC-2020-145
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
tuf
PyPI
 before 0.12.0
0.12.0
tuf
PyPI
 before 0.12.0, plus listed versions
0.10.00.10.10.10.20.11.00.11.1
Show 10 moreShow less
0.11.2.dev10.11.2.dev20.11.2.dev30.11.dev00.12.dev00.12.dev10.12.dev20.7.50.9.80.9.9
0.12.0
tuf
PyPI
 before 0.12.0, plus listed versions
0.7.50.9.80.9.90.10.00.10.1
Show 10 moreShow less
0.10.20.11.dev00.11.00.11.10.11.2.dev10.11.2.dev20.11.2.dev30.12.dev00.12.dev10.12.dev2
0.12.0

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-15163 is a high vulnerability (CVSS 8.7) in Linuxfoundation The Update Framework, published September 9, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.67%, the 52nd percentile. Fixed in tuf 0.12.0.

References

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