CVE-2025-68113

MEDIUMPre-NVD 6.56.5
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (39th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 6.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

ALTCHA is privacy-first software for captcha and bot protection. A cryptographic semantic binding flaw in ALTCHA libraries allows challenge payload splicing, which may enable replay attacks. The HMAC signature does not unambiguously bind challenge parameters to the nonce, allowing an attacker to reinterpret a valid proof-of-work submission with a modified expiration value. This may allow previously solved challenges to be reused beyond their intended lifetime, depending on server-side replay handling and deployment assumptions. The vulnerability primarily impacts abuse-prevention mechanisms such as rate limiting and bot mitigation. It does not directly affect data confidentiality or integrity. This issue has been addressed by enforcing explicit semantic separation between challenge parameters and the nonce during HMAC computation. Users are advised to upgrade to patched versions, which include version 1.0.0 of the altcha Golang package, version 1.0.0 of the altcha Rubygem, version 1.0.0 of the altcha pip package, version 1.0.0 of the altcha Erlang package, version 1.4.1 of the altcha-lib npm package, version 1.3.1 of the altcha-org/altcha Composer package, and version 1.3.0 of the org.altcha:altcha Maven package. As a mitigation, implementations may append a delimiter to the end of the salt value prior to HMAC computation (for example, ?expires=&). This prevents ambiguity between parameters and the nonce and is backward-compatible with existing implementations, as the delimiter is treated as a standard URL parameter separator.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
44
EG Risk 44/100

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)
Severity65% × 45%
Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (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 at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
39th
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 (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.

EG Severity
6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). 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 low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track 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). 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)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

December 16, 2025

Last Modified

October 7, 2026

Advisory Details (10)

Auto-updated Aug 8, 2026
Patch available. Sources: github_commit, github_release, github.
GitHub advisoryMentions a patch (unverified)

ALTCHA Proof-of-Work Vulnerable to Challenge Splicing and Replay · Advisory · altcha-org/altcha-lib · GitHub

https://github.com/altcha-org/altcha-lib/security/advisories/GHSA-6gvq-jcmp-8959
GitHub release Patch Available

v1.4.1

Patch available: altcha-org/altcha-lib 1.4.1

https://github.com/altcha-org/altcha-lib/releases/tag/1.4.1
GitHub commit Patch Available

commit cb95d83a8d08 (altcha-org/altcha-lib)

Patch available: altcha-org/altcha-lib 1.4.1 (contains commit cb95d83a8d08)

https://github.com/altcha-org/altcha-lib/commit/cb95d83a8d08e273b6be15e48988e7eaf60d5c08
GitHub commit

commit 4fd7b64cbbfc (altcha-org/altcha-lib-rb)

Fix landed in altcha-org/altcha-lib-rb commit 4fd7b64cbbfc — awaiting tagged release

https://github.com/altcha-org/altcha-lib-rb/commit/4fd7b64cbbfc713f3ca4e066c2dd466e3b8d359b
GitHub release Patch Available

v1.3.1

Patch available: altcha-org/altcha-lib-php v1.3.1

https://github.com/altcha-org/altcha-lib-php/releases/tag/v1.3.1
GitHub commit Patch Available

commit 9e9e70c864a9 (altcha-org/altcha-lib-php)

Patch available: altcha-org/altcha-lib-php v1.3.1 (contains commit 9e9e70c864a9)

https://github.com/altcha-org/altcha-lib-php/commit/9e9e70c864a9db960d071c77c778be0c9ff1a4d0
GitHub release Patch Available

Release v1.3.0

Patch available: altcha-org/altcha-lib-java v1.3.0

https://github.com/altcha-org/altcha-lib-java/releases/tag/v1.3.0
GitHub commit Patch Available

commit 69277651fdd6 (altcha-org/altcha-lib-java)

Patch available: altcha-org/altcha-lib-java v1.3.0 (contains commit 69277651fdd6)

https://github.com/altcha-org/altcha-lib-java/commit/69277651fdd6418ae10bf3a088901506f9c62114
GitHub commit

commit 4a5610745ef7 (altcha-org/altcha-lib-go)

Fix landed in altcha-org/altcha-lib-go commit 4a5610745ef7 — awaiting tagged release

https://github.com/altcha-org/altcha-lib-go/commit/4a5610745ef79895a67bac858b2e4f291c2614b8
GitHub commit

commit 09b2bad466ad (altcha-org/altcha-lib-ex)

Fix landed in altcha-org/altcha-lib-ex commit 09b2bad466ad — awaiting tagged release

https://github.com/altcha-org/altcha-lib-ex/commit/09b2bad466ad0338a5b24245380950ea9918333e

Affected Packages

(7 across 7 ecosystems)
Go(1)
PackageVulnerable rangeFix by version rangeDependents
github.com/altcha-org/altcha-lib-go—
  • every version up to 1.0.0: fixed in 1.0.0
—
Hex(1)
PackageVulnerable rangeFix by version rangeDependents
altcha0.1.0, 0.2.0
  • every version up to 1.0.0: fixed in 1.0.0
—
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
org.altcha:altcha1.1.0, 1.1.1, 1.1.2, 1.2.0
  • every version up to 1.3.0: fixed in 1.3.0
—
npm(1)
PackageVulnerable rangeFix by version rangeDependents
altcha-lib—
  • every version up to 1.4.1: fixed in 1.4.1
—
Packagist(1)
PackageVulnerable rangeFix by version rangeDependents
altcha-org/altchav0.1.0 ... v1.3.0 (11 versions)
  • every version up to 1.3.1: fixed in 1.3.1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
altcha0.1.0 ... 0.2.0 (10 versions)
  • every version up to 1.0.0: fixed in 1.0.0
—
RubyGems(1)
PackageVulnerable rangeFix by version rangeDependents
altcha0.1.0, 0.2.0, 0.2.1
  • every version up to 1.0.0: fixed in 1.0.0
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 33× 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.

Showing the most recent 95 of 206 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 5 repeat rows among the latest 100 are merged into the row they repeat. The 111 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  2. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  3. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  4. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  5. 2026-10-18 05:18 UTCEG score recompute
  6. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  7. 2026-10-16 16:39 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  8. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  9. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  10. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  11. 2026-10-12 16:47 UTCEG score recompute
  12. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  13. 2026-10-11 20:22 UTCEG score recompute
  14. 2026-10-11 18:34 UTCEG score recompute
  15. 2026-10-11 15:09 UTCEG score recompute
  16. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  17. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  18. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  19. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  20. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  21. 2026-10-07 19:22 UTCEG score recompute
  22. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  23. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  24. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  25. 2026-10-03 18:21 UTCOSV refresh
Show 70 more
  1. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  2. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  3. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  4. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  5. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  6. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  7. 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  8. 2026-09-23 13:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  9. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  10. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  11. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  12. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  13. 2026-09-16 05:14 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  14. 2026-09-15 03:10 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  15. 2026-09-14 08:49 UTCOSV refresh
  16. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  17. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  18. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  19. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  20. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  21. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  22. 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  23. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  24. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  25. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  26. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  27. 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  28. 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  29. 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  30. 2026-08-26 14:45 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  31. 2026-08-26 09:43 UTCOSV refresh
  32. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  33. 2026-08-24 14:16 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  34. 2026-08-23 00:18 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  35. 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  36. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  37. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  38. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  39. 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  40. 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  41. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  42. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  43. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  44. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  45. 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  46. 2026-08-10 23:59 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  47. 2026-08-09 23:46 UTCEG score recompute
  48. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  49. 2026-08-08 16:36 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  50. 2026-08-08 06:33 UTCEG score recompute
  51. 2026-08-07 16:27 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  52. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  53. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  54. 2026-08-04 10:37 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  55. 2026-08-03 10:35 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  56. 2026-08-02 02:26 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  57. 2026-08-01 04:15 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  58. 2026-07-30 16:27 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  59. 2026-07-30 01:30 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  60. 2026-07-27 14:13 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  61. 2026-07-27 04:39 UTCOSV refresh
  62. 2026-07-26 14:54 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  63. 2026-07-25 14:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  64. 2026-07-24 14:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  65. 2026-07-23 14:18 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  66. 2026-07-23 03:02 UTCEG score recompute
  67. 2026-07-22 14:08 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  68. 2026-07-21 15:24 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  69. 2026-07-20 17:08 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  70. 2026-07-19 14:30 UTCEPSS rescoreEPSS 0.3% · 19th percentile

Frequently asked(5)

What is CVE-2025-68113?
CVE-2025-68113 is a medium-severity vulnerability; its CVE record was published on December 16, 2025. ALTCHA is privacy-first software for captcha and bot protection. A cryptographic semantic binding flaw in ALTCHA libraries allows challenge payload splicing, which may enable replay attacks. The HMAC signature does not unambiguously bind challenge parameters to the nonce, allowing an attacker to…
When was the CVE record for CVE-2025-68113 published?
The CVE record for CVE-2025-68113 was published on December 16, 2025. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 7, 2026; the record at its source may have been updated since.
Is CVE-2025-68113 actively exploited?
CVE-2025-68113 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (39th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-68113?
CVE-2025-68113 has a CVSS base score of 6.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2025-68113?
A fix for CVE-2025-68113 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-68113

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