CVE-2025-4516

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

A fix is available — apply it.

There is an issue in CPython when using bytes.decode("unicode_escape", error="ignore|replace"). If you are not using the "unicode_escape" encoding or an error handler your usage is not affected. To work-around this issue you may stop using the error= handler and instead wrap the bytes.decode() call in a try-except catching the DecodeError.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

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%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
10%
KEV
Not listed

Published

May 15, 2025

Last Modified

July 31, 2026

Advisory Details (10)

Auto-updated Jul 30, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr, github_commit.
github_commit

commit ab9893c40609 (python/cpython)

Fix landed in python/cpython commit ab9893c40609 — awaiting tagged release

https://github.com/python/cpython/commit/ab9893c40609935e0d40a6d2a7307ea51aec598b
github_commit

commit 8d35fd1b3493 (python/cpython)

Fix landed in python/cpython commit 8d35fd1b3493 — awaiting tagged release

https://github.com/python/cpython/commit/8d35fd1b34935221aff23a1ab69a429dd156be77
github_commit

commit 73b3040f5924 (python/cpython)

Fix landed in python/cpython commit 73b3040f5924 — awaiting tagged release

https://github.com/python/cpython/commit/73b3040f592436385007918887b7e2132aa8431f
github_commit

commit 6279eb8c076d (python/cpython)

Fix landed in python/cpython commit 6279eb8c076d — awaiting tagged release

https://github.com/python/cpython/commit/6279eb8c076d89d3739a6edb393e43c7929b429d
github_commit

commit 4398b788ffc1 (python/cpython)

Fix landed in python/cpython commit 4398b788ffc1 — awaiting tagged release

https://github.com/python/cpython/commit/4398b788ffc1f954a2c552da285477d42a571292
github_commit

commit 9f69a58623bd (python/cpython)

Fix landed in python/cpython commit 9f69a58623bd — awaiting tagged release

https://github.com/python/cpython/commit/9f69a58623bd01349a18ba0c7a9cb1dad6a51e8e
github_commit

commit 69b4387f78f4 (python/cpython)

Fix landed in python/cpython commit 69b4387f78f4 — awaiting tagged release

https://github.com/python/cpython/commit/69b4387f78f413e8c47572a85b3478c47eba8142
generic

Mailman 3 [CVE-2025-4516] Use-after-free crash using bytes.decode("unicode_escape", error="ignore|replace") - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/L75IPBBTSCYEF56I2M4KIW353BB3AY74/
github_pr

gh-133767: Fix use-after-free in the unicode-escape decoder with an error handler

Fix merged in python/cpython PR #129648 on 2025-05-12 — awaiting tagged release

https://github.com/python/cpython/pull/129648
generic

Use-after-free in `unicode_escape` decoder with error handler · Issue #133767 · python/cpython · GitHub

https://github.com/python/cpython/issues/133767

Vendor Advisories for CVE-2025-4516(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 / EcosystemFixed in / PatchReleasedSource
ubuntupython3.8-venv (3.8.0-3ubuntu1~18.04.2+esm5) @ bionic2026-07-31ubuntu
redhatpython39-devel:3.9-8100020251126112422.d47b87a42025-12-18redhat

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.

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 6× in last 7d / 49× 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 159 total refreshes for this CVE.

  1. 2026-08-06 13:46 UTCEPSS rescore
  2. 2026-08-05 19:16 UTCEPSS rescore
  3. 2026-08-04 15:09 UTCEPSS rescore
  4. 2026-08-04 10:37 UTCEPSS rescore
  5. 2026-08-03 10:35 UTCEPSS rescore
  6. 2026-08-02 02:26 UTCEPSS rescore
  7. 2026-08-01 04:15 UTCEPSS rescore
  8. 2026-07-31 14:25 UTCVendor advisory
  9. 2026-07-31 14:25 UTCGHSA enrichment
  10. 2026-07-31 14:09 UTCVendor advisory
  11. 2026-07-31 14:09 UTCGHSA enrichment
  12. 2026-07-30 23:20 UTCVendor advisory
  13. 2026-07-30 23:20 UTCGHSA enrichment
  14. 2026-07-30 22:22 UTCEG score recompute
  15. 2026-07-30 22:22 UTCVendor advisory
  16. 2026-07-30 22:22 UTCGHSA enrichment
  17. 2026-07-30 16:27 UTCEPSS rescore
  18. 2026-07-30 01:30 UTCEPSS rescore
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  20. 2026-07-28 15:35 UTCEPSS rescore
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  22. 2026-07-25 14:17 UTCEPSS rescore
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  24. 2026-07-24 14:17 UTCEPSS rescore
  25. 2026-07-23 14:18 UTCEPSS rescore
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  1. 2026-07-23 02:56 UTCEG score recompute
  2. 2026-07-22 14:07 UTCEPSS rescore
  3. 2026-07-22 14:07 UTCEPSS rescore
  4. 2026-07-21 15:24 UTCEPSS rescore
  5. 2026-07-20 17:07 UTCEPSS rescore
  6. 2026-07-19 14:30 UTCEPSS rescore
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  8. 2026-07-19 02:28 UTCEPSS rescore
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  10. 2026-07-18 10:04 UTCEPSS rescore
  11. 2026-07-16 17:02 UTCEPSS rescore
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  13. 2026-07-15 16:57 UTCEPSS rescore
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  15. 2026-07-15 01:59 UTCEPSS rescore
  16. 2026-07-15 01:59 UTCEPSS rescore
  17. 2026-07-14 08:10 UTCOSV refresh
  18. 2026-07-13 22:29 UTCEPSS rescore
  19. 2026-07-13 22:29 UTCEPSS rescore
  20. 2026-07-13 06:12 UTCEPSS rescore
  21. 2026-07-11 08:27 UTCEPSS rescore
  22. 2026-07-11 08:27 UTCEPSS rescore
  23. 2026-07-09 19:09 UTCEPSS rescore
  24. 2026-07-09 19:09 UTCEPSS rescore
  25. 2026-07-08 15:15 UTCEPSS rescore
  26. 2026-07-07 13:45 UTCEPSS rescore
  27. 2026-07-06 16:27 UTCEPSS rescore
  28. 2026-07-06 16:27 UTCEPSS rescore
  29. 2026-07-06 02:23 UTCEPSS rescore
  30. 2026-07-06 02:23 UTCEPSS rescore
  31. 2026-07-05 02:30 UTCEPSS rescore
  32. 2026-07-04 06:30 UTCEPSS rescore
  33. 2026-07-02 17:01 UTCEPSS rescore
  34. 2026-07-01 15:06 UTCEPSS rescore
  35. 2026-06-30 23:22 UTCEPSS rescore
  36. 2026-06-30 23:22 UTCEPSS rescore
  37. 2026-06-29 14:06 UTCEPSS rescore
  38. 2026-06-29 14:06 UTCEPSS rescore
  39. 2026-06-28 14:07 UTCEPSS rescore
  40. 2026-06-28 14:07 UTCEPSS rescore
  41. 2026-06-28 04:55 UTCEPSS rescore
  42. 2026-06-28 04:55 UTCEPSS rescore
  43. 2026-06-27 03:08 UTCEPSS rescore
  44. 2026-06-26 05:46 UTCOSV refresh
  45. 2026-06-25 13:49 UTCEPSS rescore
  46. 2026-06-25 13:49 UTCEPSS rescore
  47. 2026-06-24 14:04 UTCEPSS rescore
  48. 2026-06-24 14:04 UTCEPSS rescore
  49. 2026-06-23 21:32 UTCEPSS rescore
  50. 2026-06-23 21:32 UTCEPSS rescore
  51. 2026-06-22 14:25 UTCEPSS rescore
  52. 2026-06-22 14:25 UTCEPSS rescore
  53. 2026-06-21 14:56 UTCEPSS rescore
  54. 2026-06-21 14:56 UTCEPSS rescore
  55. 2026-06-21 01:59 UTCEPSS rescore
  56. 2026-06-21 01:59 UTCEPSS rescore
  57. 2026-06-19 19:25 UTCEPSS rescore
  58. 2026-06-19 19:25 UTCEPSS rescore
  59. 2026-06-18 17:52 UTCEPSS rescore
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  61. 2026-06-17 17:52 UTCEPSS rescore
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  63. 2026-06-16 17:52 UTCEPSS rescore
  64. 2026-06-16 17:52 UTCEPSS rescore
  65. 2026-06-15 17:48 UTCEPSS rescore
  66. 2026-06-14 23:17 UTCEPSS rescore
  67. 2026-06-13 23:00 UTCEPSS rescore
  68. 2026-06-12 23:11 UTCEPSS rescore
  69. 2026-06-11 14:00 UTCEPSS rescore
  70. 2026-06-11 14:00 UTCEPSS rescore
  71. 2026-06-10 22:18 UTCEPSS rescore
  72. 2026-06-10 22:18 UTCEPSS rescore
  73. 2026-06-10 13:22 UTCEPSS rescore
  74. 2026-06-08 16:14 UTCEG score recompute▲ 5.90
  75. 2026-06-08 16:14 UTCVendor advisory

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-4516?
CVE-2025-4516 is a medium vulnerability published on May 15, 2025. There is an issue in CPython when using bytes.decode("unicodeescape", error="ignore|replace"). If you are not using the "unicodeescape" encoding or an error handler your usage is not affected. To work-around this issue you may stop using the error= handler and instead wrap the bytes.decode() call…
When was CVE-2025-4516 disclosed?
CVE-2025-4516 was first published in the National Vulnerability Database on May 15, 2025, with the most recent update on July 31, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-4516 actively exploited?
CVE-2025-4516 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 90.1% of all scored CVEs.
What is the CVSS score of CVE-2025-4516?
CVE-2025-4516 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2025-4516?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-4516, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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