CVE-2026-82331

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-23. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Improper link resolution before file access ('link following') vulnerability in the tar source plugin of Apache BuildStream running on Python < 3.12 allows malicious source tarballs to write files on the host, with the privileges of the user running BuildStream, via symlinks as part of source fetching. The impact of this issue is mitigated by:

* BuildStream projects should only use trusted sources in their elements as otherwise the build output can also not be trusted * Tracking a source tarball pins its SHA256 hash, which prevents MITM attacks of users that are fetching an already tracked project * When running on Python >= 3.12, BuildStream >= 2.3.0 already makes use of the Python tarfile filter functionality, which blocks the symlink escape

Users are recommended to upgrade to version 2.8.1, which fixes this issue.

CVSS v3
9.8
EG Score
9.8CRITICALhigh confidence
EG Risk
59
EG Risk 59/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
34th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 23, 2026

Last Modified

September 23, 2026

Advisory Details (2)

Auto-updated Sep 30, 2026
Fix named in the CVE record.
generic

oss-security - CVE-2026-82331: Apache BuildStream: tar source extraction escape

http://www.openwall.com/lists/oss-security/2026/09/23/9
generic

Pony Mail

https://lists.apache.org/thread/9b342631x7bvtyg0pq7zgywtl2cmy34v

Vendor Advisories for CVE-2026-82331(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 51× in last 7d / 91× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-04 12:55 UTCGHSA enrichment
  2. 2026-10-04 08:32 UTCGHSA enrichment
  3. 2026-10-04 04:11 UTCGHSA enrichment
  4. 2026-10-03 23:52 UTCGHSA enrichment
  5. 2026-10-03 19:32 UTCGHSA enrichment
  6. 2026-10-03 15:12 UTCEG score recompute
  7. 2026-10-03 15:12 UTCGHSA enrichment
  8. 2026-10-03 14:26 UTCEPSS rescore
  9. 2026-10-03 10:53 UTCGHSA enrichment
  10. 2026-10-03 06:33 UTCGHSA enrichment
  11. 2026-10-03 02:13 UTCGHSA enrichment
  12. 2026-10-02 21:54 UTCEG score recompute
  13. 2026-10-02 21:54 UTCGHSA enrichment
  14. 2026-10-02 17:57 UTCEPSS rescore
  15. 2026-10-02 17:34 UTCGHSA enrichment
  16. 2026-10-02 13:15 UTCGHSA enrichment
  17. 2026-10-02 08:55 UTCGHSA enrichment
  18. 2026-10-02 04:30 UTCGHSA enrichment
  19. 2026-10-02 00:04 UTCEG score recompute
  20. 2026-10-02 00:04 UTCGHSA enrichment
  21. 2026-10-01 19:50 UTCEPSS rescore
  22. 2026-10-01 19:38 UTCGHSA enrichment
  23. 2026-10-01 15:18 UTCGHSA enrichment
  24. 2026-10-01 10:58 UTCGHSA enrichment
  25. 2026-10-01 06:39 UTCGHSA enrichment
Show 66 more
  1. 2026-10-01 02:19 UTCGHSA enrichment
  2. 2026-09-30 22:00 UTCGHSA enrichment
  3. 2026-09-30 17:40 UTCEG score recompute
  4. 2026-09-30 17:40 UTCGHSA enrichment
  5. 2026-09-30 15:04 UTCEPSS rescore
  6. 2026-09-30 13:16 UTCGHSA enrichment
  7. 2026-09-30 08:56 UTCGHSA enrichment
  8. 2026-09-30 04:37 UTCGHSA enrichment
  9. 2026-09-30 00:15 UTCGHSA enrichment
  10. 2026-09-29 18:17 UTCEG score recompute
  11. 2026-09-29 18:17 UTCGHSA enrichment
  12. 2026-09-29 13:32 UTCGHSA enrichment
  13. 2026-09-29 09:13 UTCGHSA enrichment
  14. 2026-09-29 04:51 UTCGHSA enrichment
  15. 2026-09-29 00:31 UTCEG score recompute
  16. 2026-09-29 00:31 UTCGHSA enrichment
  17. 2026-09-28 20:10 UTCGHSA enrichment
  18. 2026-09-28 15:46 UTCEG score recompute
  19. 2026-09-28 15:46 UTCGHSA enrichment
  20. 2026-09-28 13:52 UTCEPSS rescore
  21. 2026-09-28 11:26 UTCGHSA enrichment
  22. 2026-09-28 07:06 UTCGHSA enrichment
  23. 2026-09-28 02:46 UTCGHSA enrichment
  24. 2026-09-27 22:27 UTCGHSA enrichment
  25. 2026-09-27 18:07 UTCEG score recompute
  26. 2026-09-27 18:07 UTCGHSA enrichment
  27. 2026-09-27 13:48 UTCEPSS rescore
  28. 2026-09-27 13:47 UTCGHSA enrichment
  29. 2026-09-27 09:26 UTCGHSA enrichment
  30. 2026-09-27 05:06 UTCGHSA enrichment
  31. 2026-09-27 00:45 UTCGHSA enrichment
  32. 2026-09-26 20:26 UTCGHSA enrichment
  33. 2026-09-26 16:06 UTCEG score recompute
  34. 2026-09-26 16:06 UTCGHSA enrichment
  35. 2026-09-26 15:59 UTCEPSS rescore
  36. 2026-09-26 11:45 UTCGHSA enrichment
  37. 2026-09-26 07:25 UTCGHSA enrichment
  38. 2026-09-26 03:01 UTCEG score recompute
  39. 2026-09-26 03:00 UTCGHSA enrichment
  40. 2026-09-25 22:39 UTCGHSA enrichment
  41. 2026-09-25 18:19 UTCGHSA enrichment
  42. 2026-09-25 13:17 UTCGHSA enrichment
  43. 2026-09-25 08:57 UTCGHSA enrichment
  44. 2026-09-25 04:37 UTCGHSA enrichment
  45. 2026-09-25 00:18 UTCGHSA enrichment
  46. 2026-09-24 19:58 UTCGHSA enrichment
  47. 2026-09-24 15:38 UTCEG score recompute
  48. 2026-09-24 15:38 UTCGHSA enrichment
  49. 2026-09-24 14:04 UTCEPSS rescore
  50. 2026-09-24 11:19 UTCGHSA enrichment
  51. 2026-09-24 06:59 UTCGHSA enrichment
  52. 2026-09-24 02:40 UTCGHSA enrichment
  53. 2026-09-23 22:21 UTCGHSA enrichment
  54. 2026-09-23 18:01 UTCEG score recompute
  55. 2026-09-23 18:01 UTCGHSA enrichment
  56. 2026-09-23 17:54 UTCEPSS rescore
  57. 2026-09-23 17:19 UTCGHSA enrichment
  58. 2026-09-23 16:24 UTCEG score recompute
  59. 2026-09-23 16:24 UTCGHSA enrichment
  60. 2026-09-23 15:20 UTCGHSA enrichment
  61. 2026-09-23 14:59 UTCEG score recompute▲ 9.80
  62. 2026-09-23 14:59 UTCGHSA enrichment
  63. 2026-09-23 14:59 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
  64. 2026-09-23 07:19 UTCNVD update
  65. 2026-09-23 07:11 UTCEG score recompute
  66. 2026-09-23 07:11 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-82331?
CVE-2026-82331 is a critical vulnerability published on September 23, 2026. Improper link resolution before file access ('link following') vulnerability in the tar source plugin of Apache BuildStream running on Python < 3.12 allows malicious source tarballs to write files on the host, with the privileges of the user running BuildStream, via symlinks as part of source…
When was CVE-2026-82331 disclosed?
CVE-2026-82331 was first published on September 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-82331 actively exploited?
CVE-2026-82331 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (34th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-82331?
CVE-2026-82331 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-82331?
A fix for CVE-2026-82331 is available — its CVE record says: "The impact of this issue is mitigated by: * BuildStream projects should only use trusted sources in their elements as otherwise the build output can also not be trusted * Tracking a source tarball pins its SHA256 hash,…" The vendor advisories EchelonGraph has for CVE-2026-82331 are linked in the Vendor Advisories panel on this page.

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