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.
CVE-2025-68113
“—” 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.
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5MEDIUMmedium confidence
- EG Risk
- 44EG 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, 2026ALTCHA 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-8959v1.4.1
Patch available: altcha-org/altcha-lib 1.4.1
https://github.com/altcha-org/altcha-lib/releases/tag/1.4.1commit 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/cb95d83a8d08e273b6be15e48988e7eaf60d5c08commit 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/4fd7b64cbbfc713f3ca4e066c2dd466e3b8d359bv1.3.1
Patch available: altcha-org/altcha-lib-php v1.3.1
https://github.com/altcha-org/altcha-lib-php/releases/tag/v1.3.1commit 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/9e9e70c864a9db960d071c77c778be0c9ff1a4d0Release v1.3.0
Patch available: altcha-org/altcha-lib-java v1.3.0
https://github.com/altcha-org/altcha-lib-java/releases/tag/v1.3.0commit 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/69277651fdd6418ae10bf3a088901506f9c62114commit 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/4a5610745ef79895a67bac858b2e4f291c2614b8commit 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/09b2bad466ad0338a5b24245380950ea9918333eAffected Packages
(7 across 7 ecosystems)
Go(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| github.com/altcha-org/altcha-lib-go | — |
| — |
Hex(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| altcha | 0.1.0, 0.2.0 |
| — |
Maven(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| org.altcha:altcha | 1.1.0, 1.1.1, 1.1.2, 1.2.0 |
| — |
npm(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| altcha-lib | — |
| — |
Packagist(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| altcha-org/altcha | v0.1.0 ... v1.3.0 (11 versions) |
| — |
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| altcha | 0.1.0 ... 0.2.0 (10 versions) |
| — |
RubyGems(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| altcha | 0.1.0, 0.2.0, 0.2.1 |
| — |
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.
- 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-18 05:18 UTCEG score recompute
- 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-16 16:39 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-12 16:47 UTCEG score recompute
- 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-11 20:22 UTCEG score recompute
- 2026-10-11 18:34 UTCEG score recompute
- 2026-10-11 15:09 UTCEG score recompute
- 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-07 19:22 UTCEG score recompute
- 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-03 18:21 UTCOSV refresh
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- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-23 13:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-16 05:14 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-15 03:10 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-14 08:49 UTCOSV refresh
- 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-08-26 14:45 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-08-26 09:43 UTCOSV refresh
- 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-08-24 14:16 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-08-23 00:18 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
- 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-10 23:59 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-09 23:46 UTCEG score recompute
- 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-08 16:36 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-08 06:33 UTCEG score recompute
- 2026-08-07 16:27 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-04 10:37 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-03 10:35 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-02 02:26 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-01 04:15 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-30 16:27 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-30 01:30 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-27 14:13 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-27 04:39 UTCOSV refresh
- 2026-07-26 14:54 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-25 14:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-24 14:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-23 14:18 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-23 03:02 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-21 15:24 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-20 17:08 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-07-19 14:30 UTCEPSS rescoreEPSS 0.3% · 19th percentile
Related CVEs(same CWE)
Same CWE
10 shownCWE-347
Frequently asked(5)
What is CVE-2025-68113?
When was the CVE record for CVE-2025-68113 published?
Is CVE-2025-68113 actively exploited?
What is the CVSS score of CVE-2025-68113?
How do I remediate CVE-2025-68113?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-68113
Is Your Infrastructure Affected by CVE-2025-68113?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.