CVE-2026-102633

MEDIUMPre-NVD 5.95.9
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-89028 (ENISA EUVD) · GHSA-533f-rf84-jgcc (GitHub Security Advisories)Source: ENISA EUVD

5.9EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 5.9Exploit: None knownExposed services: Not assessed

A fix is available — 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
5.9MEDIUMmedium confidence
EG Risk
27
EG Risk 27/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity59% × 45%
Impact severity (EG Severity): CVSS 5.9 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
30th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (5.9): severity, escalated by confirmed exploitation. This CVE's 5.9 is its impact severity (EG Severity), not escalated.

EG Severity
5.9 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

September 29, 2026

Last Modified

September 29, 2026

Advisory Details (5)

Auto-updated Sep 29, 2026
Patch available. Sources: github_commit, github_pr.
Web page

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
Web page

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
Web page

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 pull request

[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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatexpat-0:2.7.3-1.el10_2.72026-10-22redhat
redhatexpat-0:2.5.0-6.el9_8.72026-10-22redhat

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

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
expat2.5.0-1 ... 2.9.0-1 (34 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
expat2.7.1-2 ... 2.9.0-1 (18 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
expat2.7.1-2 ... 2.8.5-1 (16 versions)
  • every version up to 2.8.5-2: fixed in 2.8.5-2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 69× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  2. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  3. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  4. 2026-10-29 18:33 UTCEG score recompute
  5. 2026-10-29 18:33 UTCVendor advisory
  6. 2026-10-29 18:33 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  7. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  8. 2026-10-29 14:49 UTCEG score recompute
  9. 2026-10-29 14:49 UTCVendor advisory
  10. 2026-10-29 14:49 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  11. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  12. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  13. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  14. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  15. 2026-10-25 14:56 UTCEG score recompute
  16. 2026-10-24 16:31 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  17. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  18. 2026-10-23 09:28 UTCEG score recompute
  19. 2026-10-23 09:28 UTCVendor advisory
  20. 2026-10-23 09:28 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  21. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  22. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  23. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  24. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  25. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
Show 60 more
  1. 2026-10-18 05:10 UTCEG score recompute
  2. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  3. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  4. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  5. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  6. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  7. 2026-10-12 16:40 UTCEG score recompute
  8. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  9. 2026-10-11 22:18 UTCVendor advisory
  10. 2026-10-11 22:17 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  11. 2026-10-11 20:16 UTCEG score recompute
  12. 2026-10-11 18:28 UTCEG score recompute
  13. 2026-10-11 15:02 UTCEG score recompute
  14. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  15. 2026-10-10 22:16 UTCEG score recompute
  16. 2026-10-10 22:16 UTCVendor advisory
  17. 2026-10-10 22:16 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  18. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  19. 2026-10-09 22:11 UTCEG score recompute
  20. 2026-10-09 22:11 UTCVendor advisory
  21. 2026-10-09 22:10 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  22. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  23. 2026-10-08 22:10 UTCEG score recompute
  24. 2026-10-08 22:10 UTCVendor advisory
  25. 2026-10-08 22:10 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  26. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  27. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  28. 2026-10-07 22:09 UTCVendor advisory
  29. 2026-10-07 22:09 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  30. 2026-10-06 22:05 UTCEG score recompute
  31. 2026-10-06 22:05 UTCVendor advisory
  32. 2026-10-06 22:05 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  33. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  34. 2026-10-05 22:04 UTCEG score recompute
  35. 2026-10-05 22:04 UTCVendor advisory
  36. 2026-10-05 22:04 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  37. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  38. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  39. 2026-10-04 22:04 UTCVendor advisory
  40. 2026-10-04 22:04 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  41. 2026-10-03 22:04 UTCEG score recompute
  42. 2026-10-03 22:04 UTCVendor advisory
  43. 2026-10-03 22:04 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  44. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  45. 2026-10-02 22:03 UTCEG score recompute
  46. 2026-10-02 22:03 UTCVendor advisory
  47. 2026-10-02 22:03 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  48. 2026-10-01 22:02 UTCEG score recompute
  49. 2026-10-01 22:02 UTCVendor advisory
  50. 2026-10-01 22:02 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  51. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  52. 2026-09-30 21:57 UTCEG score recompute
  53. 2026-09-30 21:57 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  54. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  55. 2026-09-29 21:57 UTCEG score recompute
  56. 2026-09-29 21:57 UTCGHSA enrichmentGHSA-533f-rf84-jgcc · GitHub severity HIGH · GitHub CVSS 5.9
  57. 2026-09-29 17:31 UTCEG score recompute
  58. 2026-09-29 17:03 UTCEG score recompute
  59. 2026-09-29 16:29 UTCEG score recomputeFirst assessed: 5.9 MEDIUM
  60. 2026-09-29 16:28 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-102633?
CVE-2026-102633 is a medium-severity vulnerability; its CVE record was 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 made public?
CVE-2026-102633 was made public on September 25, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on September 29, 2026. EchelonGraph's copy of the record carries a last-modified date of September 29, 2026; the record at its source may have been updated since.
Is CVE-2026-102633 actively exploited?
CVE-2026-102633 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (30th 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?
A fix for CVE-2026-102633 is available: update to the fixed version the vendor names in its advisory. 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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