CVE-2026-56389

HIGHNVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

Score 8.6 from GitHub Security Advisory published 2026-07-29. NVD baseline CVSS 8.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp(). When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.

Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 3169c1e7a2c6acc4c59dfcf8b089896d6881925b. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.

CVSS v3
8.6
EG Score
8.6(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: Track

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
Severity86% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

July 29, 2026

Last Modified

August 24, 2026

Advisory Details (2)

Auto-updated Jul 29, 2026
No patch confirmed yet.
generic

bison.git - GNU bison (git mirror)

https://cgit.git.savannah.gnu.org/cgit/bison.git/
generic

Vulnerabilities in GNU Bison software | CERT Polska

https://cert.pl/en/posts/2026/07/CVE-2026-56389

Vendor Advisories for CVE-2026-56389(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
bison2:3.7.5+dfsg-1, 2:3.7.6+dfsg-1, 2:3.8.1+dfsg-1, 2:3.8.2+dfsg-1——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
bison2:3.8.2+dfsg-1——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
bison2:3.8.2+dfsg-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
bison2:3.8.2+dfsg-1——

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 30× in last 7d / 117× 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.

Showing the most recent 100 of 177 total refreshes for this CVE.

  1. 2026-09-15 08:09 UTCEG score recompute
  2. 2026-09-15 08:09 UTCVendor advisory
  3. 2026-09-15 08:09 UTCGHSA enrichment
  4. 2026-09-15 03:11 UTCEPSS rescore
  5. 2026-09-14 16:52 UTCVendor advisory
  6. 2026-09-14 16:51 UTCGHSA enrichment
  7. 2026-09-14 05:17 UTCVendor advisory
  8. 2026-09-14 05:17 UTCGHSA enrichment
  9. 2026-09-13 17:43 UTCEG score recompute
  10. 2026-09-13 17:43 UTCVendor advisory
  11. 2026-09-13 17:43 UTCGHSA enrichment
  12. 2026-09-13 16:47 UTCEPSS rescore
  13. 2026-09-13 06:09 UTCVendor advisory
  14. 2026-09-13 06:09 UTCGHSA enrichment
  15. 2026-09-12 18:30 UTCEG score recompute
  16. 2026-09-12 18:30 UTCVendor advisory
  17. 2026-09-12 18:30 UTCGHSA enrichment
  18. 2026-09-12 06:56 UTCVendor advisory
  19. 2026-09-12 06:56 UTCGHSA enrichment
  20. 2026-09-11 19:22 UTCEG score recompute
  21. 2026-09-11 19:22 UTCVendor advisory
  22. 2026-09-11 19:22 UTCGHSA enrichment
  23. 2026-09-11 14:53 UTCEPSS rescore
  24. 2026-09-11 07:27 UTCGHSA enrichment
  25. 2026-09-10 19:53 UTCEG score recompute
Show 75 more
  1. 2026-09-10 19:53 UTCGHSA enrichment
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-10 07:17 UTCGHSA enrichment
  4. 2026-09-09 07:50 UTCEG score recompute
  5. 2026-09-09 07:50 UTCGHSA enrichment
  6. 2026-09-08 22:01 UTCEPSS rescore
  7. 2026-09-07 20:52 UTCEG score recompute
  8. 2026-09-07 20:52 UTCVendor advisory
  9. 2026-09-07 20:52 UTCGHSA enrichment
  10. 2026-09-07 16:01 UTCEPSS rescore
  11. 2026-09-06 18:24 UTCEG score recompute
  12. 2026-09-06 18:24 UTCVendor advisory
  13. 2026-09-06 18:24 UTCGHSA enrichment
  14. 2026-09-06 13:47 UTCEPSS rescore
  15. 2026-09-06 06:50 UTCGHSA enrichment
  16. 2026-09-05 19:07 UTCVendor advisory
  17. 2026-09-05 19:07 UTCGHSA enrichment
  18. 2026-09-05 05:21 UTCEG score recompute
  19. 2026-09-05 05:21 UTCVendor advisory
  20. 2026-09-05 05:20 UTCGHSA enrichment
  21. 2026-09-04 11:56 UTCEG score recompute
  22. 2026-09-04 11:56 UTCVendor advisory
  23. 2026-09-04 11:56 UTCGHSA enrichment
  24. 2026-09-04 05:07 UTCEPSS rescore
  25. 2026-09-02 14:12 UTCEPSS rescore
  26. 2026-09-01 22:47 UTCEG score recompute
  27. 2026-09-01 22:47 UTCVendor advisory
  28. 2026-09-01 22:47 UTCGHSA enrichment
  29. 2026-09-01 13:54 UTCEPSS rescore
  30. 2026-09-01 04:40 UTCEPSS rescore
  31. 2026-09-01 00:01 UTCVendor advisory
  32. 2026-09-01 00:01 UTCGHSA enrichment
  33. 2026-08-30 22:28 UTCEG score recompute
  34. 2026-08-30 22:28 UTCVendor advisory
  35. 2026-08-30 22:28 UTCGHSA enrichment
  36. 2026-08-30 19:17 UTCEPSS rescore
  37. 2026-08-30 10:55 UTCEG score recompute
  38. 2026-08-30 10:55 UTCVendor advisory
  39. 2026-08-30 10:55 UTCGHSA enrichment
  40. 2026-08-30 01:22 UTCEPSS rescore
  41. 2026-08-29 23:21 UTCEG score recompute
  42. 2026-08-29 23:21 UTCVendor advisory
  43. 2026-08-29 23:21 UTCGHSA enrichment
  44. 2026-08-28 21:42 UTCEPSS rescore
  45. 2026-08-28 01:56 UTCEG score recompute
  46. 2026-08-28 01:56 UTCVendor advisory
  47. 2026-08-28 01:56 UTCGHSA enrichment
  48. 2026-08-27 14:25 UTCEPSS rescore
  49. 2026-08-27 14:22 UTCVendor advisory
  50. 2026-08-27 14:22 UTCGHSA enrichment
  51. 2026-08-27 02:46 UTCVendor advisory
  52. 2026-08-27 02:46 UTCGHSA enrichment
  53. 2026-08-26 15:12 UTCEG score recompute
  54. 2026-08-26 15:12 UTCVendor advisory
  55. 2026-08-26 15:12 UTCGHSA enrichment
  56. 2026-08-26 14:46 UTCEPSS rescore
  57. 2026-08-26 03:38 UTCVendor advisory
  58. 2026-08-26 03:38 UTCGHSA enrichment
  59. 2026-08-25 16:04 UTCEG score recompute
  60. 2026-08-25 16:04 UTCVendor advisory
  61. 2026-08-25 16:03 UTCGHSA enrichment
  62. 2026-08-25 13:49 UTCEPSS rescore
  63. 2026-08-25 04:29 UTCEG score recompute
  64. 2026-08-25 04:29 UTCVendor advisory
  65. 2026-08-25 04:29 UTCGHSA enrichment
  66. 2026-08-24 16:55 UTCEG score recompute▲ 1.80
  67. 2026-08-24 16:55 UTCVendor advisory
  68. 2026-08-24 16:55 UTCGHSA enrichment
  69. 2026-08-24 16:23 UTCNVD updateCVSS v3 → 8.6 · severity → HIGH
  70. 2026-08-24 00:45 UTCVendor advisory
  71. 2026-08-24 00:45 UTCGHSA enrichment
  72. 2026-08-22 23:31 UTCEG score recompute
  73. 2026-08-22 23:31 UTCVendor advisory
  74. 2026-08-22 23:31 UTCGHSA enrichment
  75. 2026-08-21 23:49 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-56389?
CVE-2026-56389 is a high vulnerability published on July 29, 2026. GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without…
When was CVE-2026-56389 disclosed?
CVE-2026-56389 was first published in the National Vulnerability Database on July 29, 2026, with the most recent update on August 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56389 actively exploited?
CVE-2026-56389 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 94.6% of all scored CVEs.
What is the CVSS score of CVE-2026-56389?
CVE-2026-56389 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-56389?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56389, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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