CVE-2026-76641

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-20. The CNA's CVSS baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 4 sources updated this week
7.5EG
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: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100CISA 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
Severity75% × 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
26th
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 partial (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

August 20, 2026

Last Modified

October 1, 2026

Advisory Details (3)

Auto-updated Aug 20, 2026
Patch available. Sources: github_pr, github_commit.
generic

Expat Out-of-Bounds Read via dtdCopy | Advisories | VulnCheck

https://www.vulncheck.com/advisories/expat-out-of-bounds-read-via-dtdcopy
github_commit

commit 98599f6dcc2b (libexpat/libexpat)

Fix landed in libexpat/libexpat commit 98599f6dcc2b — awaiting tagged release

https://github.com/libexpat/libexpat/commit/98599f6dcc2b460410881fe420f5f55d6bec63bf
github_pr

[CVE-2026-76641] lib: Fix out-of-bounds read from hash table entries created by dtdCopy

Fix merged in libexpat/libexpat PR #1331 on 2026-08-20 — awaiting tagged release

https://github.com/libexpat/libexpat/pull/1331

Vendor Advisories for CVE-2026-76641(2)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibexpat1-dev (2.2.5-3ubuntu0.9+esm5) @ bionic2026-10-05ubuntu
redhatexpat-main-2.8.4-0.1.hum12026-09-08redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
expat—
  • every version up to 2.8.4-r0: fixed in 2.8.4-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
expat—
  • every version up to 2.8.4-r0: fixed in 2.8.4-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
expat—
  • every version up to 2.8.4-r0: fixed in 2.8.4-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
expat—
  • every version up to 2.8.4-r0: fixed in 2.8.4-r0
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 35× in last 7d / 121× 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 187 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-76641?
CVE-2026-76641 is a high vulnerability published on August 20, 2026. Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XMLExternalEntityParserCreate. A struct size mismatch between ELEMENTTYPE members causes storeAtts to read the attIndex…
When was CVE-2026-76641 disclosed?
CVE-2026-76641 was first published on August 20, 2026, with the most recent update on October 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-76641 actively exploited?
CVE-2026-76641 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-76641?
CVE-2026-76641 has a CVSS base score of 7.5 (the CNA's own assessment, by vulncheck; NVD's own analysis pending).
How do I remediate CVE-2026-76641?
A fix for CVE-2026-76641 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-76641 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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