CVE-2026-102633

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreHIGH confidence

Score 5.9 from GitHub Security Advisory (severity: HIGH) published 2026-09-29. A secondary CVSS source baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 5 sources updated this week
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 5.9Exploit: None knownExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial of service.

CVSS v3
5.9
EG Score
5.9MEDIUMhigh confidence
EG Risk
27
EG Risk 27/100CISA 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
Severity59% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines until it ships, then apply the release.
EPSS PROB
0.3%
EPSS %ILE
26th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines until it ships, then apply the release.

Exploitation none (CISA Vulnrichment) · Automatable no (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

September 29, 2026

Last Modified

September 29, 2026

Advisory Details (5)

Auto-updated Sep 29, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libexpat-2.7.2-through-2.8.5-integer-overflow-in-expat-realloc
generic

GitHub - libexpat/libexpat: :herb: Fast streaming XML parser written in C99 with >90% test coverage; moved from SourceForge to GitHub · GitHub

https://github.com/libexpat/libexpat
generic

libexpat/expat/lib/xmlparse.c at R_2_8_5 · libexpat/libexpat · GitHub

https://github.com/libexpat/libexpat/blob/R_2_8_5/expat/lib/xmlparse.c#L1003
github_commit

commit 209801d7fbaf (libexpat/libexpat)

Fix landed in libexpat/libexpat commit 209801d7fbaf — awaiting tagged release

https://github.com/libexpat/libexpat/commit/209801d7fbaf07ab74bae8cb32dd2ab9e5846118
github_pr

[CVE-REQUESTED] lib: Replace `assert` with runtime overflow check in `expat_realloc` for 32bit platforms

Fix merged in libexpat/libexpat PR #1392 on 2026-09-25 — awaiting tagged release

https://github.com/libexpat/libexpat/pull/1392

Vendor Advisories for CVE-2026-102633(2)

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 20× in last 7d / 20× 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. 2026-10-03 22:04 UTCEG score recompute
  2. 2026-10-03 22:04 UTCVendor advisory
  3. 2026-10-03 22:04 UTCGHSA enrichment
  4. 2026-10-03 14:25 UTCEPSS rescore
  5. 2026-10-02 22:03 UTCEG score recompute
  6. 2026-10-02 22:03 UTCVendor advisory
  7. 2026-10-02 22:03 UTCGHSA enrichment
  8. 2026-10-01 22:02 UTCEG score recompute
  9. 2026-10-01 22:02 UTCVendor advisory
  10. 2026-10-01 22:02 UTCGHSA enrichment
  11. 2026-10-01 19:49 UTCEPSS rescore
  12. 2026-09-30 21:57 UTCEG score recompute
  13. 2026-09-30 21:57 UTCGHSA enrichment
  14. 2026-09-30 15:02 UTCEPSS rescore
  15. 2026-09-29 21:57 UTCEG score recompute
  16. 2026-09-29 21:57 UTCGHSA enrichment
  17. 2026-09-29 17:31 UTCEG score recompute
  18. 2026-09-29 17:03 UTCEG score recompute
  19. 2026-09-29 16:29 UTCEG score recompute
  20. 2026-09-29 16:28 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-102633?
CVE-2026-102633 is a medium vulnerability published on September 29, 2026. libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or…
When was CVE-2026-102633 disclosed?
CVE-2026-102633 was first published on September 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-102633 actively exploited?
CVE-2026-102633 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-102633?
CVE-2026-102633 has a CVSS base score of 5.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-102633?
An upstream fix for CVE-2026-102633 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-102633 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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